A genuine modern slavery due diligence process is not a policy document sitting in a drawer. It is a live set of checks, on the supply chain, on labour providers, and on individual workers, repeated often enough to catch problems before they become a legal, reputational or human one. This article sets out what the Modern Slavery Act 2015 actually requires, what real due diligence looks like in a construction or facilities management supply chain, and a checklist procurement buyers can use to assess whether a contractor's own due diligence is more than a paragraph in a tender response.

A genuine modern slavery due diligence process is not a policy document sitting in a drawer. It is a live set of checks, on the supply chain, on labour providers, and on individual workers, repeated often enough to catch problems before they become a legal, reputational or human one. This article sets out what the Modern Slavery Act 2015 actually requires, what real due diligence looks like in a construction or facilities management supply chain, and a checklist procurement buyers can use to assess whether a contractor's own due diligence is more than a paragraph in a tender response.

What the Modern Slavery Act 2015 actually requires

Section 54 of the Modern Slavery Act 2015 requires a commercial organisation to publish an annual slavery and human trafficking statement if it supplies goods or services, carries on business (or part of a business) in the UK, and has a total annual turnover of £36 million or more, including the turnover of any subsidiaries wherever they operate.

The statement must set out the steps the organisation has taken during that financial year to ensure slavery and human trafficking is not taking place in its own business or in any part of its supply chain, or state plainly that it has taken no such steps. The law does not mandate a minimum standard of action; it mandates transparency about whatever action was or was not taken. Current statutory guidance recommends the statement cover six areas: organisational structure and supply chains, policies, due diligence processes, risk assessment, key performance indicators, and staff training. The statement needs board (or equivalent) approval and a named director's signature, must be published on the organisation's website homepage if it has one, and must go out within 30 days to anyone who requests a copy in writing if it does not. The Secretary of State can seek a High Court injunction against an organisation that fails to comply.

What this means for a buyer: a section 54 statement is a transparency requirement, not a certificate of a clean supply chain. A well-written statement from a supplier is a starting point for scrutiny, not a substitute for it. Below the £36 million threshold, an organisation has no statutory duty to publish anything at all: this is precisely where a buyer's own due diligence has to do more of the work, because a smaller subcontractor or labour provider may have no public statement to check against.

The regulator has changed: GLAA is now the Fair Work Agency

Anyone researching this topic against older material will find repeated references to the Gangmasters and Labour Abuse Authority (GLAA). That body no longer exists in that form. On 7 April 2026 its functions, along with HMRC's National Minimum Wage enforcement team and the Employment Agency Standards Inspectorate, transferred into the new Fair Work Agency (FWA), an executive agency of the Department for Business and Trade created under the Employment Rights Act 2025. The FWA now runs the gangmasters licensing scheme, investigates labour exploitation, and holds the enforcement powers the GLAA previously held. Procurement teams still using "GLAA licence" as shorthand in supplier questionnaires should update that language: the licence itself, and the standards behind it, continue; the issuing body's name does not.

It is also worth being precise about scope, because this is where the licensing regime is most often overstated. A gangmaster's licence from the FWA is a legal requirement only for businesses supplying labour into agriculture, horticulture, shellfish gathering, and associated food processing and packaging. Construction and facilities management labour supply sit outside that mandatory scheme. That does not make the FWA's licensing standards irrelevant to a buyer in these sectors: they cover exactly the areas (pay, accommodation, transport, working hours, training) that also matter in a construction or FM labour supply chain, but a buyer should not ask a construction subcontractor "are you FWA/GLAA licensed" as if it were a compliance gate; it is not one, because the licence does not apply to their sector. The right question is whether the labour provider applies equivalent standards voluntarily, and whether it can evidence that.

What genuine due diligence looks like in a construction or FM supply chain

Right to work checks. Every worker on site, employed directly or supplied through a labour provider, needs a right to work check carried out to current Home Office guidance before their first shift: either a manual document check, an online check using a share code, or a certified digital identity check for British and Irish nationals. A buyer assessing a contractor's due diligence should ask who carries out these checks (the contractor, or a labour provider on their behalf), how the checks are recorded, and what happens when a labour provider's own paperwork is the only evidence on file, because relying entirely on a third party's assurance, with no spot-checking, is a common weak point.

Labour provider vetting. Where a contractor uses agency or subcontracted labour, ask how that labour provider was selected and how it is monitored on an ongoing basis, not just at onboarding. Membership of the Association of Labour Providers (ALP), a not-for-profit trade body that promotes responsible recruitment and publishes due diligence guidance for the sector, is a reasonable signal of intent, though membership itself is not a guarantee; it should sit alongside direct evidence such as payslip sampling, accommodation checks where relevant, and confirmation that workers are not paying recruitment fees to secure the work.

Recruitment red flags. Ask a contractor what they train site and recruitment managers to look for. Genuine red flags include workers who cannot produce their own identity documents (a common sign documents are being held by a third party), pay that is consistently and unexplainably below the rate advertised, workers transported to and from site as a group with no independent means of travel, an unusual concentration of workers tied to a single introducer or agency, and reluctance or inability of a worker to speak for themselves about their own terms of employment. Official guidance on identifying potential victims of modern slavery sets out a fuller list and should be the reference point, not a contractor's own informal list.

Worker interview protocols. A due diligence process that never involves speaking to workers directly, away from their immediate supervisor or agency contact, has a structural blind spot: coercion and control are usually invisible in paperwork. Ask whether a contractor's process includes any direct engagement with agency workers, even informally, and whether there is a route for a worker to raise a concern that does not go through the person supplying or supervising them.

Subcontractor auditing. Due diligence has to extend past the first tier. Ask how far down the supply chain a contractor's checks actually reach: do they audit only their direct subcontractors, or do they require those subcontractors to demonstrate the same standard with their own labour suppliers. A statement that only covers "our supply chain" in the abstract, with no description of how far that visibility extends, is a sign the process has not been tested against a real multi-tier chain.

A practical checklist for assessing a contractor's due diligence

Before appointing a contractor or labour-supplying subcontractor, ask for evidence, not assurance, against each of the following:

1. Turnover and statement status. Is the organisation above the £36 million threshold, and if so, can they produce a current, board-signed section 54 statement published on their own website homepage?
2. Right to work process. Who performs the check, using which of the three lawful methods, and how is the result recorded and retained?
3. Labour provider identity. Which agencies or labour providers do they use, and are those providers ALP members or able to evidence equivalent standards?
4. Onboarding beyond paperwork. Is there any direct contact with individual workers as part of onboarding, separate from the supplying agency?
5. Red flag training. Can they name what site or recruitment managers are trained to look for, and point to when that training last happened?
6. Reporting route. Is there a whistleblowing or concern-raising channel that a worker (not just a manager) could plausibly use, and is it publicised on site?
7. Subcontractor reach. How far down their own supply chain does their due diligence extend, and can they describe (not just assert) how a second-tier labour supplier is checked?
8. Audit frequency. Are labour providers and subcontractors reassessed periodically, or only at initial appointment?

A contractor that can answer all eight with specifics, rather than general reassurance, is treating this as an operational process. One that answers only with "we take it seriously" or points solely to a section 54 statement has not shown you how the process actually works on site.

Where this leaves AOG's own position

AOG publishes its own Modern Slavery Statement at ascentonsite.group/modern-slavery, made in line with section 54, and is a member of the Association of Labour Providers. That statement is under periodic review and some organisation-specific detail on it is still being finalised; this article describes the regulatory and sector landscape a buyer needs to understand, not a claim about the completeness of any single organisation's own statement, including AOG's.

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