The Chain Below the Contract: What Public Buyers Do Not Publish About Subcontractors

Public procurement in the UK has become better at publishing the headline: the buyer, the supplier, the value, the dates. It is far less good at publishing the chain beneath. When a council or NHS trust awards a contract, the name on the notice is often the prime contractor — the organisation that holds the agreement, manages the relationship and takes the fee. The firms that actually deliver the work can sit one or two tiers down, invisible in the record unless something goes wrong.

The Ferret reviewed procurement documents and FOI responses from 14 public bodies in 2026, covering contracts in digital services, adult social care transport, facilities management and school building maintenance. In each case, the prime contractor was named. In most, there was no published list of subcontractors. Where lists existed, they were partial, undated or stripped of the values attached to each tier.

The prime contractor as front door

One 2026 digital transformation contract awarded by a London borough was valued at £4.2m. The award notice named a consultancy as supplier. A subsequent FOI response said the council did not hold a central record of subcontractors, though contract conditions required the prime to seek consent before appointing firms to deliver 'material elements' of the work. The council said subcontractor information was held within individual project files and was not compiled for publication.

An NHS trust in the north of England awarded a £2.8m facilities management contract to a national provider. The trust told The Ferret that 11 subcontractors were engaged on the contract. Only two were named in the contract award notice. The trust said the remaining names were 'commercially sensitive' and that disclosure could undermine the prime contractor's ability to manage its supply chain.

A county council's £6.1m school maintenance framework named a construction group as the prime supplier. Internal contract monitoring records, released after a four-month FOI process, showed that around 40% of the contract value had been subcontracted. The records listed six firms by name but did not show which schools each had worked on, the value of each package or whether the council had approved each appointment.

What is collected, what is published

Public bodies usually collect some subcontractor data. Contract terms often require the prime to notify the buyer before appointing subcontractors above a threshold, and to flow down obligations on pay, safety, data protection and modern slavery. Contract managers may hold delivery schedules, site lists and invoices that reveal the second tier.

The gap is between collection and publication. Award notices on Contracts Finder and Find a Tender provide a standard set of fields: the buyer, the supplier, the value, the duration and the nature of the work. Subcontractor fields are limited. A buyer can include additional information in free-text sections, but there is no consistent requirement to name firms below the prime or to update the record when the chain changes.

FOI can fill some of the gap, but not reliably. Requests for subcontractor lists often produce a patchwork of responses. Some bodies release names and values; others release names only; others refuse on commercial confidentiality grounds. The outcome depends less on the size of the public interest than on how the contract was drafted and how the buyer's records were kept.

Why the second tier matters

Accountability is not only about who signs the contract. It is about who does the work. If a subcontractor fails to meet safety standards, underpays staff, mishandles personal data or becomes insolvent mid-delivery, the public body's contractual remedy may lie with the prime. But the public interest lies with the service and the money. Residents, patients and pupils experience the second tier directly.

Scrutiny bodies face the same blind spot. Councillors sitting on audit committees can question the prime contractor's performance. They are less able to question a chain of firms they cannot see. External auditors can follow the money through the buyer's ledger, but tracing it through a prime contractor's supply chain requires access that is not routinely granted or published.

The rules in outline

The Procurement Act 2023 was intended to improve transparency, and its central digital platform is meant to make contract information easier to find. But the published record still centres on the prime relationship. The Act's transparency provisions do not create a standing public register of subcontractors for every above-threshold contract.

That leaves a familiar pattern. Public bodies can point to the award notice and say the contract is transparent. Prime contractors can point to commercial confidentiality and say their supply chains are a matter for them. The firms doing the work remain one step removed from the record — and from the scrutiny that public money is meant to attract.

What scrutiny would require

A more accountable system would not need to publish every purchase order. It would need a consistent minimum: the name of each subcontractor above a defined value, the value band of the work, the date of appointment and any changes to the chain during the contract. That information could sit alongside the contract record and be updated when the prime reports a change.

Contract clauses could require consent for subcontracting and disclosure of the resulting chain as a condition of that consent. FOI responses could be made more consistent by guidance that treats the existence of a subcontractor, and the value band of the work, as publishable by default. None of this would remove the need for commercial judgment. It would make the judgment visible.

The Ferret's review does not show that public bodies are hiding second-tier failures on a systematic scale. It shows something narrower and more corrosive: a record that stops at the front door. The prime contractor is named. The chain below is not. For as long as that remains true, accountability for public money depends on questions that the published record never prompts.