Treasure finds on a development site: what happens next

If something on your site meets the statutory definition of treasure, someone has 14 days to report it to the coroner, and failing to do so without reasonable excuse is a criminal offence. The Treasure Act 1996 applies to a development site exactly as it applies to a field with a metal detector on it, and the duty falls on the person who found the object.

That is the part developers most often get wrong. The obligation does not sit with the archaeological contractor by default, and it does not wait until the end of the dig.

What counts as treasure

The definition is technical, and guessing is a poor strategy. In outline, treasure covers metallic objects other than coins that are at least 300 years old and contain at least 10 per cent gold or silver by weight, and coins of the same age where the find contains enough of them, with the threshold number depending on the precious metal content. It also covers objects found with treasure, prehistoric base-metal objects found as part of a multiple find, and anything that would previously have been treasure trove.

A further class was designated in 2023 covering certain metal objects of significant historical, archaeological or cultural interest that fall outside the age and metal tests. Verify the current definition on the gov.uk guidance before deciding anything, because the categories have been amended more than once.

Single base-metal objects, pottery, worked flint and most other archaeological material are not treasure. They are still archaeologically valuable and still need recording, but a different process applies to them.

The duty to report

The finder must notify the coroner for the area within 14 days, running from the day of the find or the day the finder first believed or had reason to believe the object might be treasure. A landowner or occupier who comes to believe a find has been made without being reported has their own reason to act.

The 14 days is not a target. It is a statutory limit with an offence attached, so the site protocol should treat a possible treasure find as a same-day escalation to the site manager and the archaeological contractor, not something to mention at the weekly meeting.

Who you actually contact

In practice, reporting runs through the Finds Liaison Officer for the area, who works within the Portable Antiquities Scheme and is based at a local museum or archaeology service. The officer records the object, identifies it, and handles the notification to the coroner.

Find that person's contact details before you start on site and put them in the written scheme of investigation alongside the site contacts. An induction slide with a photograph of what a possible treasure find looks like, the instruction to stop and secure rather than to clean or pocket, and one telephone number does more than any amount of policy wording.

Record the findspot properly. A grid reference, a context, a photograph in place and the depth are worth far more than the object on its own, and a coin bag with no provenance is close to worthless as evidence.

The coroner, valuation and reward

The coroner decides whether a find is treasure. Where it is, the object vests in the Crown, and museums are then given the opportunity to acquire it.

Where a museum wishes to acquire, an independent valuation committee of specialists recommends a market value, and a reward of that amount is paid. The reward is normally divided between the finder and the landowner, commonly in equal shares, though a written agreement between them can set a different split. Where no museum wants the object, it is usually disclaimed and returned.

Archaeologists working on a commercial excavation do not claim rewards. The code of practice issued under the Act asks them to waive any entitlement, on the basis that they are already being paid to do the work, and reputable contractors write that into their terms.

Agreements to have in place first

Settle ownership and reward before the first trench opens, in writing, with everyone who will be on the ground.

• The contract with the archaeological contractor, stating that its staff waive any reward entitlement and confirming the reporting protocol.
• An agreement with the landowner where you are not the freeholder, covering the reward share and who deals with the museum.
• Any agreement with a metal detecting club or individual invited on to survey the site, covering access, supervision, reporting, recording standards and ownership.
• A clause in the main contractor's appointment requiring immediate reporting and prohibiting unrecorded removal of finds.

A dispute about a reward split, discovered after a hoard is in a museum's hands, is slow and unpleasant. It is also entirely avoidable at contract stage.

Metal detecting and scheduled ground

Inviting detectorists on to a site before groundworks can be genuinely useful, because it recovers material from the ploughsoil that machine stripping would otherwise destroy. Do it under supervision, with a written agreement, and with finds recorded to a defined standard.

Unauthorised detecting is a different matter. Removing objects from land without permission is theft, and doing it on a scheduled monument, or using a detector there at all without consent from the Secretary of State, is a separate offence under the Ancient Monuments and Archaeological Areas Act 1979. Sites with known potential are targeted at night during construction, so fencing, lighting and security patrols are a reasonable response where the archaeological desk-based assessment has flagged the risk.

The effect on the programme

A treasure find does not stop the site. What it stops is work in that immediate area, until the object and its context have been properly excavated and recorded, which for a single object is usually a matter of hours or a day.

A hoard is different. Hoards deserve block lifting and excavation under laboratory conditions, which means a conservator becomes involved, and it means the surrounding deposits are investigated to establish whether there is more. Where a find changes the understanding of the site, the county archaeologist may reasonably ask for the scope of the archaeological field evaluation or the mitigation strategy to be revisited.

Build a contingency into the programme where the desk-based work suggests the potential is real, and where the same ground also has to deliver habitat, read the note on archaeology and biodiversity net gain on one site, because both want undisturbed ground.

Finds that are not treasure

Most of what comes off an archaeological site is not treasure and never will be. Pottery, animal bone, worked stone, building material, single copper-alloy objects and iron work make up the bulk of any assemblage.

Those finds belong to the landowner in the ordinary case, subject to whatever the contract says, and they are recorded through the site archive rather than through the coroner. Voluntary recording with the Portable Antiquities Scheme is still worth doing for stray finds made outside the formal excavation, because it adds to the national record at no cost to you.

The archive has to go somewhere. Agree the receiving museum early, because deposition charges and museum acceptance policies affect the budget, and set the significance of the assemblage out in the heritage statement supporting the application.

This is general guidance, not legal advice. Treasure law carries criminal penalties and the definitions have been amended, so check the current guidance and take archaeological advice before acting on a find.

Draft the heritage and archaeology documents for a site in minutes at PlanScope, then have them reviewed by a suitably qualified archaeologist.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.