Prepared and maintained by Cambridge Development Archaeologyfor development teams working across Cambridge and Cambridgeshire.
Sources, review dates and corrections →What actually happens on site
An archaeologist attends agreed groundworks — topsoil strip, foundation trenches, service runs, attenuation basins — and records archaeological features as they are exposed by your plant. Work is not normally stopped. Where something significant appears, there is a short, agreed pause to record it properly before the ground is taken further.
The archaeologist works to an approved written scheme, keeps a site record, recovers finds, and produces a report afterwards. The presence is monitoring, not excavation: the intention is to capture information, not to strip and dig the site in advance.
When an authority will accept it
A watching brief is accepted where archaeological potential is real but low, or where the surviving remains are expected to be sparse, and where the development's ground disturbance is limited. It is a proportionate response to a modest risk.
- Small infill or single-plot sites within an existing settlement footprint
- Sites where evaluation has already been carried out and found little or nothing
- Limited groundworks — service corridors, extensions, individual buildings
- Previously developed land where earlier disturbance is documented
- Sites where the archaeological advisor's concern is specific and narrow, such as a single known feature
When it is the wrong instrument
On an open greenfield site with good archaeological potential, a watching brief is a commercial trap rather than a saving. If substantial remains appear during your groundworks, you are discovering them at the most expensive possible moment: plant on site, programme committed, and no agreed budget for excavation.
That is the scenario a prior evaluation is designed to prevent. On larger schemes we would rather argue for evaluation early — while the cost of being wrong is a survey, not a stoppage — than accept a watching brief that shifts risk into the construction phase.
Cost and programme effect
Watching brief cost is driven by attendance days, not by area. A short intermittent attendance across a few weeks of groundworks is inexpensive. A continuous attendance across a long enabling-works programme is not, and it is worth agreeing in advance which operations genuinely require presence.
Programme effect is usually small, but it is not nil: the report and any finds work still have to be completed before the condition is discharged. Build that reporting period into your programme rather than discovering it at handover.
What to send us
The condition wording, the site plan with your groundworks sequence, and any earlier archaeological work on the site. From those three we can say whether a watching brief is likely to be accepted, how many attendance days it realistically needs, and where the risk of a stoppage sits.