Archaeological Desk-Based Assessment: What It Covers and What It Cannot Tell You

What goes into it

A desk-based assessment gathers and interprets existing evidence for a defined site and a study area around it. No ground is broken. The output is an assessment of archaeological potential, significance and the likely impact of your proposals.

• Historic Environment Record data for the site and surrounding study area
• Designated assets: scheduled monuments, listed buildings, conservation areas, registered parks
• Historic maps, tithe and enclosure mapping, and Ordnance Survey editions
• Aerial photography and, where available, lidar and geophysical survey results
• Records of previous archaeological work on and adjacent to the site
• Geology, soils and topography, which govern both survival and detectability
• A site walkover, where access allows, to check current ground conditions and prior disturbance

Why it is submitted with an application

National planning policy expects an applicant to describe the significance of heritage assets affected by a proposal, including assets with archaeological interest, before the application is determined. Where potential exists, a desk-based assessment is normally the minimum that satisfies that expectation.

Getting it in with the application is also the cheapest route. Where the assessment is absent, an authority commonly either requests it as a validation point or attaches a broader pre-commencement condition than it would otherwise have needed — and broad conditions are expensive to discharge.

What it cannot do

A desk-based assessment cannot confirm the presence, absence, extent or condition of buried remains. It assesses likelihood from existing records, and the records for most Cambridgeshire greenfield sites are incomplete. An assessment concluding 'moderate potential' is an honest statement, not a weak one.

This is why a DBA frequently recommends evaluation rather than replacing it. Anyone promising that an assessment alone will dispose of archaeological risk on an open site is overstating what the method can deliver.

Where it saves money

The commercial value is in the targeting. A good assessment narrows the area of concern, identifies which parts of a site are already disturbed, and gives you the argument for a proportionate scope of fieldwork. A weak, templated assessment leaves the authority to assume potential across the whole site, and the resulting trenching plan is larger than it needed to be.

It is also the right document to commission before land acquisition, when the decision you are making is whether to bid at all.