Historic environment desk-based assessment

A historic environment desk-based assessment gathers what is already known about a site's archaeology and heritage, from records, maps, LiDAR and earlier reports, to judge what may survive and how a development could affect it.

Last updated 25 October 2026 · By Gitwix Limited

This guide is for archaeological units and heritage consultants preparing an assessment in England, and for anyone checking one. It sets out what planning policy and the Chartered Institute for Archaeologists (CIfA) ask for, then takes the work part by part: the site boundary and study area, the gazetteer, the designated assets, the figures, the sources, the limitations and the Historic Environment Record (HER) search. For each part it says what Field Archaeology does today and what is still yours to do.

What is a desk-based assessment?

CIfA's Standard and guidance for historic environment desk-based assessment defines good practice for the work. It was first published in December 2014 and updated in January 2017 and October 2020. CIfA members and Registered Organisations must comply with its Standard and should follow its guidance. The Standard opens:

Desk-based assessment will determine, as far as is reasonably possible from existing records, the nature, extent and significance of the historic environment within a specified area.

In a development context, the Standard goes on, the assessment establishes the impact of the proposal on that significance, or identifies the need for further evaluation to do so, so that reasoned decisions can be made on whether to mitigate, offset or accept it. The guidance describes the work as an analysis of existing written, graphic, photographic and electronic information, to identify the likely heritage assets and their significance and the character of the study area, including the settings of heritage assets.

When does planning policy ask for one?

In England the requirement is in the National Planning Policy Framework, published on 17 August 2026, whose chapter 20 sets out policy for the historic environment as policies HE1 to HE10.

Where a development proposal involves, or has the potential to involve, a heritage asset with archaeological interest, an appropriate desk-based assessment should be undertaken and, where necessary, a field evaluation.

Paragraph 1 of the same policy asks that proposals affecting heritage assets come with an assessment of the significance of the assets affected, including any contribution made by their setting, and of the proposal's potential effect on it, in proportion to the assets' importance. It adds that ‘the relevant historic environment record should be referred to in making this assessment, and appropriate expertise employed where necessary’. Policy HE3 says that local planning authorities ‘should maintain or have access to a Historic Environment Record’.

Guidance written before August 2026 refers to the Framework's old numbered paragraphs. The requirement for a desk-based assessment now sits in policy HE5.

What does the CIfA standard ask for?

The guidance that comes with the Standard sets out good practice. These are the points that shape an assessment most, with their paragraph numbers:

• An agreed scope. The work follows a written specification or project design agreed by all relevant parties (3.2.1). Within planning the brief usually comes from the planning archaeologist, and a specification should be agreed with them in advance (3.2.4).
• The HER first. Contact the relevant HER before starting (3.3.7).
• Every source. Consider all appropriate sources and assess their relevance and reliability. List every source consulted, productive or not, and every relevant source not consulted, with the reason (3.3.6).
• A visit. Unless access is restricted, visit the study area, and say in the report whether a visit took place (3.3.9).
• Significance. In England, consider each asset's archaeological, historic, architectural and artistic interest (3.4.1).
• The report. Its minimum contents include a non-technical summary, a clear map of the study area, the method and sources consulted, the assets and their significance, the effects, a conclusion with a confidence rating, illustrations at appropriate scales, supporting data in tables or appendices, and references (3.5.3). Figures should be clearly numbered and easily referenced to the National Grid (Annex 2).
• Deposit. Subject to any confidentiality in the contract, copies go to the HER and an OASIS form is completed within six months of the report (3.5.5).
• Copyright. Acknowledge what you copy or cite, and observe the copyright conditions of sources such as HERs and Ordnance Survey maps (3.6.5).

Which parts can Field Archaeology help with?

Field Archaeology puts the open national records, the Environment Agency's LiDAR and historic Ordnance Survey maps on one map, and turns an area into a report, a set of files and maps printed to scale. It gathers the open evidence. It does not search the HER, visit the site or make the judgements the standard asks for, and it does not write the assessment.

A desk-based assessment builder is in development. This page describes the atlas as it is today.

Site boundary and study area

Find the site by National Grid reference, postcode or place name in the search box, then draw the boundary with Draw an area on the ruler menu, tapping each corner. A boundary you already have as a KML or GPX file comes in through Import GPX or KML on the same menu. Saved, the boundary becomes a mark on your account, with your note and the names of the layers that were on. Its card gives the grid reference of its centre and its area, and offers an area report and the LiDAR heights for it.

A boundary in a shapefile or GeoJSON can be laid over the map with Your own data, which reads it on your device without uploading it. Reports are made from marks and from the map view, not from Your own data, so save the boundary as KML in your GIS and import that, or trace it with Draw an area.

The brief or the agreed specification sets the size of the study area; the CIfA standard does not fix one. For a circle, use Draw a circle: tap the centre, then the edge, and the saved circle's card gives its radius. For any other shape, draw it as an area. An area report covers up to 20 km across.

Make two reports, one for the site and one for the study area. A report lists everything in the area it is given, and does not separate what lies within the boundary from what lies around it. A buffer at an exact distance round an irregular boundary is a job for QGIS or ArcGIS: export your marks as KML, buffer the boundary, save the buffer as KML and import it.

The introduction should give the study area's size, surface geology and topography (Annex 2). The report gives the area's size, and the LiDAR and the Elevation profile show its shape, with a height every metre along a saved line up to 5 km long. The Geology layer gives only the bedrock, from the British Geological Survey's map at 1:625,000, so look to larger-scale mapping for the surface geology.

The gazetteer

Tap the mark and choose Area report for this area. The report gathers the area's records under eight headings: designated heritage assets, listed buildings, designated wildlife sites, features mapped from the air, historic records, sites in the period layers, Domesday places, and Portable Antiquities Scheme finds. Each row gives a name, a type, the record's own number, linked to its entry with the publisher where there is one, and a National Grid reference.

The page shows up to 150 rows under each heading, and the downloads hold every row: CSV, a zipped shapefile, and GeoJSON on the British National Grid (EPSG:27700) or in latitude and longitude. Each row carries its section, dataset, publisher, licence, record number, title, type, period, grid reference, easting and northing, latitude and longitude, and link. The shapefile opens straight into QGIS and ArcGIS, with a README on its licences and accuracy. Export this view gives the same files for the map view without the report, and a report can be printed, saved as a PDF or kept in Your files.

A National Heritage List entry appears once, however many layers hold it. What the report does not do is number the entries or measure them from the site. Give each entry your own number and use the same numbers on the figures. Distances can be worked out in a spreadsheet from the CSV's eastings and northings and those of the site's centre. For an outline, such as a registered park, the CSV gives its centre, so measure to its nearest edge in GIS from the shapefile, which keeps the whole outline.

When the HER search comes back, merge its records into the same table, matching on National Heritage List entry numbers where the HER gives them. Grid references in the report are worked out from each record's published position: to 10 m for most records, to the 1 km square for Portable Antiquities Scheme finds, and to the centre of the outline for an area.

Designated heritage assets

The report's first section lists the scheduled monuments, registered parks and gardens, registered battlefields, World Heritage Sites and protected wrecks whose boundary reaches into the area, from Historic England's National Heritage List for England. The second lists listed buildings by grade, from the same list. The third lists Natural England's designated wildlife sites, read live from Natural England: Sites of Special Scientific Interest, National Nature Reserves, Special Protection Areas, Special Areas of Conservation and Ramsar wetlands.

Two cautions. The report reads copies of the national datasets that the atlas keeps, not Historic England's live service, so open each entry from its number and check it against the list itself, which Historic England updates daily. And the report covers only the area you drew: an asset beyond it can still be affected through its setting, which policy HE5 asks you to take into account.

Some assets are not in the atlas at all: conservation areas, buildings on a local heritage list, and non-designated assets that only the HER records. Ask the local planning authority and the HER for them.

Figures: LiDAR and map regression

CIfA asks for a clear map of the study area and illustrations at appropriate scales, numbered and referenced to the National Grid. Print a map to scale draws the map around the crosshair at 1:1,250, 1:2,500, 1:5,000, 1:10,000 or 1:25,000, on A4, or on A3 when no MapTiler map is showing. Each sheet carries National Grid lines and figures if you want them (every 100 m up to 1:5,000, every kilometre beyond) with how far grid north lies from true north, and a scale bar, a north arrow, the layers shown, their sources and the method of any LiDAR view. Print at 100 per cent: fitting to the page changes the scale.

Mind the licence. The base map, the historic maps and the terrain shading come through MapTiler, whose terms allow prints of them for internal use only, and a print that shows them says so; the same goes for the map picture at the head of an area report. A report submitted with a planning application is a public document, so for its figures ask MapTiler first or use maps licensed for publication.

LiDAR

LiDAR measures heights from the air, and the Environment Agency's terrain model keeps those of the bare ground, so earthworks show as banks, ditches and mounds. The atlas shows the Environment Agency's own hillshade of its 1 m composite terrain model and eleven further views drawn from the same model, among them multi-light relief, local relief, sky view, red relief and openness. Each brings out different features, and Historic England advises using several:

Even when one visualisation seems particularly useful it is good practice to use as many different types of visualisation as possible to obtain a comprehensive overview of the archaeology.

Name the view in every LiDAR caption, credit the heights to the Environment Agency with its attribution statement and the Open Government Licence v3.0, and give the date you used the view; How to cite has the exact form. LiDAR visualisations sets out how each view is drawn, and Maiden Castle in LiDAR shows this frame in eight views. The views can sit 1 to 4 m off the Environment Agency's own hillshade, because they are placed with the Ordnance Survey Helmert transformation.

For figures you draw yourself, LiDAR heights (GeoTIFF) downloads the Environment Agency's terrain model for the rectangle round a mark or the map view, up to 5 km a side, and its last-return and first-return surface models if you tick them. The files come exactly as the Agency serves them, on the British National Grid with heights in metres above Ordnance Datum Newlyn, zipped with a README that lists the surveys behind each file and their dates, the licence and the credit line. That dates the LiDAR for your method statement.

Map regression

Map regression works back through successive maps to see when fields, buildings and earthworks appear and disappear. The atlas has Ordnance Survey maps of England from 1885 to 1961, from the National Library of Scotland: from the one-inch with hills of 1885 to 1903 to the one-inch seventh series of 1955 to 1961, with the six-inch County Series of 1888 to 1913 between; Historic maps lists them. Fade a map over today's map or the LiDAR with the slider on the map, then switch series to step through the editions.

The atlas's maps begin in 1885. Earlier maps, such as tithe and enclosure maps, estate plans and the first edition Ordnance Survey maps, are in record offices and with the HER, and the National Library of Scotland's own website has the first edition six-inch maps of England. In Devon, the Tithe fields 1840s layer gives each field's name, owner, occupier, use and acreage from the tithe survey.

The licence above applies here too: the historic maps in the atlas come through MapTiler, so a regression figure for a published report needs map images licensed for publication. How to cite explains how to take a sheet from the National Library of Scotland under its terms.

The sources consulted

All sources consulted should be listed in the report, whether or not they have been productive.

An area report ends with Sources and licences: each dataset that returned records for the area, with its publisher and licence. It names only the datasets that found something, so add those that returned nothing; Data and licences lists every dataset in the atlas. Every record card on the map ends with its source, its licence, its record number and a Cite button, which copies a Harvard reference with the date and the grid reference. Cite the record, not the map.

Then add the sources outside the atlas:

• the HER search, and the reports and archives it points to;
• unpublished fieldwork reports: the grey literature indexed in OASIS and held in the Archaeology Data Service library;
• aerial photographs, in the Historic England Archive and the HER;
• maps before 1885, tithe and enclosure awards, estate papers and other documents in record offices;
• geotechnical information such as borehole logs, where the client has it;
• published studies and the regional research agenda.

Historic England says that ‘aerial photographs, and the mapping derived from them, should be an intrinsic part of any assessment of the historic environment’. The atlas has Historic England's mapping, under features mapped from the air, but not the photographs. Compare dates divides the map in two: one side as it is now, the other earlier aerial imagery from the Esri Wayback archive or crop stress read from Sentinel-2 satellite data, now and in the drought summers of 2018 and 2022, which can reveal buried features. Treat what it shows as a lead to follow up in the archives.

Limitations

Every area report states its own limits:

The county Historic Environment Record (HER), which holds the fullest record of sites, finds, events and reports, is not published openly and is not in this report. Nor are unpublished fieldwork reports (the grey literature in OASIS and the Archaeology Data Service library), the Historic England Archive's aerial photographs, or anything on historic maps that has not been recorded. For a desk-based assessment, ask the HER for a search of this area.

A limitations section built on the atlas should add these:

• Copies of the lists. The designations and records in the report are copies kept for the atlas, while Natural England's sites are read live. Check designations against the National Heritage List itself.
• Aerial mapping. Historic England's aerial mapping is made project by project and added to as projects are completed. An empty section can mean that no project has reached the area, not that nothing is there.
• Finds. Portable Antiquities Scheme findspots are published to the 1 km square, so a find may lie up to a kilometre outside the area and finds just outside it may be missed. They show where people have searched and reported as well as where material lies, and the atlas holds part of the Scheme's records, not all of them.
• LiDAR. The Environment Agency built its 2022 composite from surveys flown between June 2000 and April 2022, each accurate to about 15 cm in height. It records the surface of the ground, so it cannot show buried remains that leave no trace there, and Historic England notes that lidar ‘cannot reveal all the feature types that can be recorded by other means’.
• Open and volunteer data. Some rows come from OpenStreetMap, Wikidata and Wikipedia, which volunteers edit, and Domesday places are positioned from Wikidata with what the book records summarised from Wikipedia. Weigh each source's reliability, as the standard asks.
• Positions. Coordinates are converted with the Ordnance Survey Helmert transformation, usually within 2 m of OSTN15 and up to about 4 m out in the far south-west. Use OSTN15 where survey accuracy matters.
• Gaps on the day. If a dataset cannot be read when the report is made, the report says so: make it again. A large area can reach the report's limit of 3,000 Portable Antiquities Scheme finds, and the report says that too.

The standard also asks for a discussion of how the choice of sources bears on the reliability of the conclusions, and for a confidence rating in the conclusion. Those are yours to write.

The HER search

Every part of England is covered by a Historic Environment Record, kept for its council or national park. It holds the fullest list of an area's known sites, finds, excavations and reports, much of it on no national list. Policy HE5 asks for it to be referred to, and the CIfA standard asks you to contact it before you start.

Find the HER, on the dashboard, names the HER for the map view from Historic England's HER boundaries, and every area report names it for its own area. Where an area crosses a boundary, each HER is listed, the one holding the centre first. Each card gives the HER's host and the area it covers, its online search if it has one, how to ask for a search, and its charges as published, with their source and the date they were checked. Below low water it points to Historic England's Marine Historic Environment Record service.

Write a search request opens an email to the HER, headed with the area's grid reference, giving the area's centre and extent as grid references and asking you to say what the work is, who it is for, what you need and how the results will be used and shared, which is what HERs ask to know.

The directory behind the cards covers England's 83 HERs and was compiled on 23 and 24 October 2026 from each HER's own pages, its Heritage Gateway entry or its Historic England profile. All 83 give an email contact, 38 have a search online and 70 publish their charges. Charges change, so confirm the fee with the HER before you commission a search.

When you write, ask what CIfA lists: which digital images and maps the HER holds that could be used, such as scanned tithe maps and aerial photographs; whether other assessments cover the area or its neighbours; and which sources the HER has already used in any appraisal of the scheme. When the results come back, merge them into the gazetteer and list the search among your sources.

What still needs professional judgement?

The atlas gathers evidence. The assessment is the judgement made from it, by people competent for the role (3.3.4). That includes:

• agreeing the scope, the study area and the sources with the local authority's historic environment adviser;
• judging the relevance and reliability of each source;
• reading the LiDAR and the maps, and setting aside features made by geology or recent farming;
• visiting the site, unless access is restricted, and saying whether you did;
• assessing the significance of each asset, including any contribution made by its setting;
• judging the potential for remains that no record yet holds;
• assessing the effect of the proposal in the terms of policy HE5: a positive effect, no effect, harm and its degree, or total loss;
• the conclusion and its confidence rating;
• recommendations for further work, which within planning are in most circumstances for the planning archaeologist;
• depositing the report with the HER and completing the OASIS form.

Like an aerial photograph, a lidar-derived image often appears misleadingly simple to interpret. To ensure the best results from a survey, the interpretation should be made by someone with the necessary skills and experience.

Questions and answers

Sources

1. Chartered Institute for Archaeologists (2020) Standard and guidance for historic environment desk-based assessment. Reading: CIfA. Available at: https://www.archaeologists.net/sites/default/files/2023-11/CIfA-SandG-DBA-2020.pdf (Accessed: 25 October 2026).
2. Environment Agency (2022) LIDAR Composite Digital Terrain Model (DTM), 1m. Available at: https://www.data.gov.uk/dataset/01b3ee39-da3f-47b6-83da-dc98e73a461f/lidar-composite-digital-terrain-model-dtm-1m (Accessed: 25 October 2026).
3. Historic England (2018) Using Airborne Lidar in Archaeological Survey: The Light Fantastic. Swindon: Historic England. Available at: https://historicengland.org.uk/images-books/publications/using-airborne-lidar-in-archaeological-survey/ (Accessed: 25 October 2026).
4. Historic England (no date) Aerial Investigation and Mapping. Available at: https://historicengland.org.uk/research/methods/airborne-remote-sensing/aerial-investigation/ (Accessed: 25 October 2026).
5. Ministry of Housing, Communities and Local Government (2026) National Planning Policy Framework, chapter 20: Conserving and enhancing the historic environment, policies HE1 to HE10. Available at: https://www.gov.uk/guidance/national-planning-policy-framework-chapter-20-conserving-and-enhancing-the-historic-environment-he1-10 (Accessed: 25 October 2026).