Responsible Supply Chains: A Practical Guide to Modern Slavery Due Diligence

Modern slavery is not a distant problem confined to overseas factories. The UK's National Crime Agency and the Home Office both recognise that victims of forced labour, debt bondage and human trafficking are found in UK and Irish supply chains too — in car washes, agriculture, construction, cleaning contracts, hospitality and the lower tiers of manufacturing. For anyone working in procurement, HR or supply chain management, knowing how to spot the warning signs and build proper due diligence into supplier and recruitment processes isn't a niche compliance topic — it's a core part of doing the job responsibly. This guide sets out what the law requires, where the risk concentrates, the red flags to watch for, and the practical steps that turn a policy document into something that actually protects people. It pairs well with structured CPD courses covering workplace ethics and compliance, which give this subject the depth a single article can't.

What "modern slavery" covers

Modern slavery is an umbrella term used in UK law for a cluster of offences: slavery, servitude, forced or compulsory labour, and human trafficking for exploitation. It doesn't require chains or physical confinement. In practice it looks like workers who can't leave a job because of debt, threats or confiscated documents; people paid far below the legal minimum wage with deductions they never agreed to; or recruitment agencies charging jobseekers a fee to secure work that leaves them beholden to whoever "found" them the role. Because these arrangements are deliberately hidden, they surface most often through inconsistencies noticed by an alert manager, auditor or colleague — which is exactly why front-line awareness matters as much as policy wording.

The UK Modern Slavery Act 2015 and section 54 statements

The Modern Slavery Act 2015 is the main UK legislation in this area. Section 54, headed "Transparency in Supply Chains," requires commercial organisations with a total annual turnover of £36 million or more that carry on business (or part of a business) in the UK to publish an annual slavery and human trafficking statement. The statement must be approved by the board (or equivalent management body) and signed by a director, and organisations are expected to publish it within six months of their financial year end, in a prominent place on their homepage. Statements can also be submitted to the government's official modern slavery statement registry.

Section 54 doesn't prescribe a single format, but the government's statutory guidance recommends statements address six areas:

• The organisation's structure, business and supply chains
• Its policies on slavery and human trafficking
• Due diligence processes in relation to slavery and trafficking in its business and supply chains
• The parts of its business and supply chains where there is a risk of slavery or trafficking, and the steps taken to assess and manage that risk
• Its effectiveness in ensuring slavery and trafficking isn't taking place, measured against appropriate performance indicators
• The training on modern slavery and trafficking available to staff

Crucially, a company below the £36 million threshold is not legally required to publish a statement — but many still adopt one voluntarily, and any organisation supplying into a larger client's contract will often be asked to demonstrate its own anti-slavery practices as part of due diligence, regardless of size. Understanding how this connects to wider ethical obligations is worth revisiting alongside a broader grounding in ethical decision-making at work.

Ireland: a different legal picture, the same practical risk

Ireland does not currently have a direct equivalent of section 54 requiring a standalone annual transparency statement. Human trafficking and forced labour are addressed through Ireland's criminal law framework and coordinated nationally through the government's National Action Plan to Prevent and Combat Human Trafficking. For Irish businesses, the practical exposure often comes indirectly — through EU-level supply chain due diligence obligations that are being phased in for larger companies, and through commercial pressure: any Irish supplier selling into a UK group captured by section 54, or into a multinational with its own ethical sourcing policy, will typically be asked to evidence the same due diligence a UK counterpart would need. Irish and UK procurement teams working across both jurisdictions are best served by applying the higher UK-style standard consistently, rather than treating the two markets differently.

Where the risk concentrates

Modern slavery risk isn't spread evenly. The Home Office, the Gangmasters and Labour Abuse Authority (GLAA) and independent research consistently point to the same higher-risk areas:

A useful discipline is to map not just direct (tier one) suppliers but the labour providers and subcontractors sitting beneath them — that's where visibility usually breaks down and where exploitation is most likely to be hidden.

Red flags in supply chains

Individually, none of the following proves exploitation is happening — but a cluster of them in one supplier relationship should trigger closer scrutiny:

• Pricing that is implausibly low compared to sector norms, suggesting labour costs are being suppressed
• Reluctance to allow site visits, worker interviews, or share subcontractor lists
• Workers transported to and from the workplace in groups by the same individual, who also handles their documents or pay
• Wage payments made in cash to a third party rather than directly to the worker, or unexplained deductions
• The same address, bank account or contact details used by multiple "separate" supplier entities
• High and unexplained staff turnover, or an inability to produce basic employment records on request
• Use of unregistered or unlicensed labour providers in sectors (such as agriculture, food processing, horticulture and shellfish gathering) where GLAA licensing is legally required

Red flags in recruitment

Because trafficking and forced labour so often begin at the point of recruitment, HR and hiring teams — whether recruiting directly or through an agency — need their own set of warning signs:

• Recruitment fees charged to the worker. Legitimate UK recruitment should never charge a jobseeker for finding them work. A worker who has paid a fee to get a job is immediately more vulnerable to control by whoever collected it.
• Withheld identity or immigration documents. A worker who says an employer or agency is "holding" their passport or right-to-work documents "for safekeeping" is describing a classic control mechanism, not routine administration.
• Debt bondage. Workers who describe owing money for transport, accommodation, visa costs or the job itself — and having that debt deducted from wages in a way that never seems to reduce — are describing a coercive arrangement, not a normal loan.
• Contract substitution. The terms, pay or role a worker signed up for overseas differ substantially from what they're actually given once they arrive.
• Living and working for the same controller. Accommodation tied to the job, controlled by the same person who supplies the work, with rent deducted directly from pay, restricts a worker's ability to leave.
• Inconsistent or scripted answers. In interviews or right-to-work checks, a worker who cannot answer basic questions about their own pay, hours or employer, or who is closely "helped" by an accompanying third party, warrants a private follow-up conversation.

Staff who conduct interviews, onboarding or supplier audits should know they can raise a concern without proving it first — this overlaps with the kind of speak-up culture covered in guidance on managing conflicts of interest, where the principle is the same: flag early, let the right process investigate.

Practical due diligence steps

Turning awareness into a working control means embedding a few concrete steps into everyday procurement and HR processes:

• Map the supply chain beyond tier one. Ask direct suppliers to identify their own labour providers and subcontractors, particularly in higher-risk categories like agriculture, construction and facilities services.
• Build anti-slavery clauses into contracts. Require suppliers to confirm compliance with the Modern Slavery Act, cooperate with audits, and flow the same requirements down to their own subcontractors.
• Check labour provider licensing where relevant. In sectors GLAA regulates, confirm the labour provider holds a current licence before engaging them.
• Verify recruitment fee policies directly with workers, not just agencies. Agency assurances that "no fees are charged" should be checked against what workers themselves report where possible.
• Run risk-based, not blanket, supplier due diligence. Prioritise higher-risk sectors, geographies and labour-intensive contracts for deeper checks and site visits.
• Train the people who actually meet workers. Site managers, HR interviewers and procurement leads dealing with agency labour need practical training on the red flags above, not just a policy to sign.
• Give people a route to report concerns confidentially. A whistleblowing or speak-up channel that staff and workers trust is often how exploitation actually comes to light.
• Review and publish the section 54 statement annually (where the threshold applies), with genuine board sign-off rather than a copy-pasted update of last year's wording.

These steps work best as part of a wider integrity framework rather than a standalone checklist — they sit close to due diligence expected under anti-bribery and corruption compliance, since both rely on the same supplier-vetting and speak-up infrastructure.

FAQs

Does every UK business need a modern slavery statement?

No. The legal requirement under section 54 applies only to commercial organisations with an annual turnover of £36 million or more that carry on business in the UK. Smaller organisations aren't legally obliged to publish one, though many choose to as good practice or because a larger client requires it as a condition of contract.

What's the difference between modern slavery and poor working conditions?

Poor conditions — low pay within legal limits, difficult hours, weak management — are an employment standards issue. Modern slavery involves an element of coercion or deception that removes a person's genuine freedom to leave: withheld documents, debt bondage, threats, or recruitment fees that trap someone in a job. The two can overlap, which is exactly why red flags need investigating rather than dismissing.

Who enforces modern slavery rules in UK supply chains?

Several bodies play a role. The Gangmasters and Labour Abuse Authority (GLAA) licenses labour providers in specific high-risk sectors and investigates labour exploitation; the police and National Crime Agency investigate criminal trafficking and forced labour offences; and the Home Office maintains the statutory guidance and the modern slavery statement registry that section 54 statements can be submitted to.

What should I do if I suspect modern slavery in a supplier or colleague's situation?

Raise it through your organisation's whistleblowing or safeguarding channel rather than confronting the suspected controller directly, which can put the potential victim at greater risk. Document what you observed factually and pass it to whoever manages supplier compliance, HR or your designated safeguarding lead so it can be assessed and, where appropriate, referred on.

Modern slavery due diligence isn't a box-ticking exercise for a compliance file — it's a practical skill for anyone who signs off a supplier, interviews a candidate, or manages a contract with agency labour. Learnsignal's CPD courses build exactly this kind of applied workplace compliance knowledge, helping procurement, HR and supply chain professionals turn policy into practice with confidence.