In 2023, a car wash in Kent was raided by the Gangmasters and Labour Abuse Authority. Inside, officers found six men living in a shipping container behind the premises. They worked twelve-hour days, six days a week. They were paid below minimum wage — when they were paid at all. Their identity documents had been confiscated by the owner. Three of them were working under coerced identities — using documents belonging to other people, provided by the trafficker who brought them to the UK.
The car wash served hundreds of local customers every week. None of them knew. Nor did the landlord, the council, or the business's suppliers. The exploitation was hidden in plain sight, behind a legitimate-looking business facade.
This is not an isolated case. According to the National Referral Mechanism, which records potential victims of modern slavery referred by first responders, there were 16,938 referrals in the UK in 2024 — a 15% increase from the previous year. Labour exploitation was the most common type, accounting for over a third of all referrals.
Modern slavery is not a historical problem confined to other countries. It is a present-day reality in the UK economy, embedded in supply chains that businesses interact with every day.
What the law requires
The Modern Slavery Act 2015 is the primary legislation governing modern slavery in the UK. It creates criminal offences for slavery, servitude, forced labour, and human trafficking. It also imposes specific obligations on businesses.
The transparency statement (Section 54)
Any commercial organisation carrying on business in the UK with an annual turnover of £36 million or more must publish an annual modern slavery statement. The statement must describe the steps the organisation has taken during the financial year to ensure that slavery and human trafficking are not taking place in its own business or supply chains.
The statement must be approved by the board of directors (or equivalent) and signed by a director. It must be published on the organisation's website with a prominent link from the homepage.
The Home Office guidance on modern slavery statements recommends that statements cover:
- The organisation's structure, business, and supply chains
- Its policies in relation to slavery and human trafficking
- Its due diligence processes
- The parts of its business and supply chains where there is a risk of slavery
- How it measures the effectiveness of its response
- Training available to staff
The legal requirement is to publish a statement. The law does not prescribe what the statement must contain — only that it must describe the steps taken, or state that no steps have been taken. In practice, however, a statement that says "we have done nothing" carries significant reputational risk and is increasingly attracting regulatory attention.
Beyond Section 54: the wider legal landscape
The transparency statement obligation has a £36 million threshold, which excludes most SMEs. But the underlying prohibition on modern slavery applies to all businesses, regardless of size. And several other legal obligations create indirect duties that affect smaller organisations:
The criminal offence of forced labour (Section 1). Any person who holds another person in slavery or servitude, or requires them to perform forced or compulsory labour, commits an offence punishable by life imprisonment. This applies regardless of business size.
Failure to prevent (proposed). The UK government has signalled its intention to introduce a "failure to prevent" offence for modern slavery, similar to the existing failure to prevent bribery under the Bribery Act 2010. If enacted, this would make organisations criminally liable if modern slavery occurs in their operations or supply chains and they failed to take reasonable steps to prevent it.
The Fair Work Agency and labour exploitation. The FWA, which incorporates the former GLAA's enforcement functions, has a mandate to address labour exploitation across the UK economy. Its consolidated powers — including walk-in inspection, information sharing, and civil penalties — create a more effective enforcement mechanism than the previous fragmented system.
Proceeds of Crime Act 2002. If a business benefits financially from modern slavery — for example, by using a supplier that exploits workers to offer below-market prices — it may be liable under proceeds of crime legislation.
Where modern slavery occurs in UK supply chains
The sectors most affected by modern slavery in the UK are those that rely on low-skilled, high-volume manual labour, particularly where workers are vulnerable due to immigration status, language barriers, or economic desperation.
Agriculture and food processing. The Gangmasters and Labour Abuse Authority has identified agriculture as a high-risk sector for labour exploitation. Seasonal workers, often sourced through intermediaries, may work long hours for below minimum wage. Accommodation provided by the employer — which is then deducted from wages — can amount to debt bondage. The seasonal worker compliance challenges in agriculture are well documented.
Construction. Labour supply chains in construction can involve multiple layers of subcontracting, with each layer creating distance between the main contractor and the individual worker. Workers at the bottom of these chains may have no employment contract, no right to work documentation, and no access to grievance mechanisms. The main contractor may be entirely unaware of conditions several subcontractor layers below.
Care sector. Domestic servitude and labour exploitation in care settings are a growing concern. Vulnerable workers — often migrants on restrictive visas — may be tied to a single employer, unable to change jobs without losing their immigration status. The fear of deportation is used as a control mechanism. The staffing pressures in care create conditions where exploitation can take root.
Cleaning and facilities management. Commercial cleaning is another sector where labour supply chains are opaque and workers are vulnerable. Cleaning contracts are often won on price, creating pressure to minimise labour costs — which can lead to minimum wage violations, excessive hours, and exploitation.
Hospitality. Hotels, restaurants, and fast food outlets — particularly those using agency or temporary workers — face modern slavery risks. The International Labour Organisation has identified hospitality as a globally high-risk sector for forced labour.
Car washes and nail bars. Hand car washes and nail salons have been repeatedly identified by UK enforcement agencies as high-risk premises for modern slavery. The business model — cash-based, labour-intensive, low-margin — creates the economic incentive for exploitation.
The warning signs
Businesses interacting with supply chains should be alert to indicators of modern slavery. No single indicator is conclusive, but a pattern of indicators warrants investigation.
Workers who appear controlled. Workers who are accompanied by a third party who speaks for them, who are reluctant to speak directly, or who appear fearful or anxious may be under the control of a trafficker or exploitative employer.
Below-market pricing. If a supplier offers prices significantly below market rate, the question is how. If the answer is labour cost — and the service is labour-intensive — the cost saving may be coming from exploitation. A cleaning contract that is 40% below the next lowest bid is not necessarily efficient. It may be exploitative.
Reluctance to allow access. A supplier that resists visits, avoids questions about working conditions, or discourages direct communication between the client and the workers may be hiding something.
Workers living at the workplace. In sectors like agriculture, car washes, and domestic work, workers living on the premises can indicate employer-controlled accommodation that amounts to debt bondage.
Identity documents held by the employer. Workers whose passports or identity documents are held by the employer or a third party — rather than in their own possession — are exhibiting one of the strongest indicators of modern slavery.
High turnover and frequent substitution. A supplier that frequently changes the workers it sends — or where workers appear and disappear without explanation — may be cycling people through exploitative arrangements.
Workers unable to confirm basic terms. If workers cannot tell you their rate of pay, their hours, their employer's name, or how to contact their employer, they may not be in a genuine, voluntary employment relationship.
What due diligence looks like in practice
Due diligence is not a one-time exercise. It is an ongoing process of assessment, monitoring, and response.
1. Map your supply chain
Identify every supplier, contractor, and intermediary that provides goods or services to your business. For each one, assess the labour exploitation risk based on sector, geography, business model, and the nature of the work. High-risk relationships — those involving low-skilled manual labour, opaque supply chains, or vulnerable worker populations — require more intensive due diligence.
2. Assess suppliers against modern slavery indicators
For high-risk suppliers, conduct or request:
- Evidence of their own modern slavery policy and statement
- Confirmation of how they verify their workers' identities and right to work
- Evidence of direct employment relationships (contracts, payslips, working time records)
- Confirmation that workers retain their own identity documents
- Evidence of grievance and whistleblowing mechanisms
- Willingness to allow site visits and worker interviews
3. Verify worker identities independently
One of the most powerful due diligence tools is also one of the simplest: confirm that the workers in your supply chain are who they claim to be. Modern slavery frequently involves coerced identity — victims working under documents that do not belong to them, or under entirely fabricated identities. If you cannot verify that a worker's identity is genuine, you cannot know whether they are working voluntarily.
This is where identity verification and right to work compliance intersect with anti-slavery due diligence. A robust right to work check does more than satisfy immigration obligations — it confirms that the person working is the person whose documents were checked, and that those documents are genuine. When workers are using coerced or stolen identities, this check is the point at which exploitation can be detected.
4. Establish reporting channels
Workers who are being exploited need a way to report it — one that does not go through their exploiter. Businesses should provide confidential reporting mechanisms that workers at any level of the supply chain can access. The Modern Slavery Helpline (0800 0121 700) is a national resource, but businesses can supplement this with their own confidential channels.
The Fair Work Agency also accepts intelligence from workers and the public. Making workers aware that they can report concerns directly to an enforcement body — without going through their employer — is an important safeguard.
5. Act on findings
Due diligence that identifies concerns but takes no action is not due diligence. It is documented awareness. If your assessment reveals indicators of modern slavery in a supplier relationship, you must act — whether that means escalating the concern to enforcement agencies, requiring the supplier to remediate, or terminating the relationship.
The Home Office guidance is clear that the goal is not to avoid all risk — that is impossible in complex supply chains. The goal is to take reasonable steps to identify and address risk. Reasonable steps include mapping, assessing, monitoring, and responding. They do not include closing your eyes and hoping for the best.
The role of identity verification in anti-slavery efforts
Identity verification is not typically discussed as an anti-slavery tool. But it should be.
Modern slavery depends on control — control of workers' movement, their earnings, their housing, and critically, their identity. Traffickers confiscate documents. They provide false documents. They force victims to work under identities that are not their own.
Every time a business verifies the identity of a worker — genuinely verifies, not just glances at a document — it creates a moment where coerced identity can be detected. A worker whose biometric data does not match their documents. A worker whose share code returns a different name. A worker who cannot answer basic questions about the identity they are presenting.
These are not just compliance failures. They are potential indicators of exploitation. And the business that detects them is in a position to intervene — to alert enforcement, to protect the worker, and to break the chain of exploitation.
Certifyd's Right to Work Portal verifies worker identities at the point of engagement — matching the person to their documents, checking against authoritative databases, and creating an auditable record that supports both immigration compliance and modern slavery due diligence. When identity verification catches a discrepancy, it may be catching something far more serious than a paperwork error.