Case study: Supply chain traceability & transparency — a city or utility pilot and the results so far

When the Greater Manchester Combined Authority (GMCA) launched its Supply Chain Transparency Programme in 2023, fewer than 12% of the region's 1,400 public procurement contracts included any form of supply chain traceability requirements. By mid-2025, that figure had reached 67%, and the programme had surfaced 38 previously undetected instances of modern slavery risk, prevented an estimated 14,000 tonnes of CO2 from entering public sector supply chains, and generated a measurable 9% cost reduction across pilot categories through better supplier visibility. The GMCA pilot stands as one of the most rigorously documented municipal supply chain transparency initiatives in the UK, offering transferable lessons for any city or utility seeking to move beyond compliance checklists toward genuine supply chain visibility.

Why It Matters

UK local authorities collectively spend approximately GBP 90 billion annually on goods and services, making them among the largest buyers in the economy (Local Government Association, 2025). Despite this purchasing power, most councils have minimal visibility beyond their direct (Tier 1) suppliers. A 2024 survey by the Chartered Institute of Procurement and Supply found that only 18% of UK public sector organisations could identify suppliers beyond Tier 2, and just 6% had real-time visibility into Tier 3 or deeper (CIPS, 2024).

This blind spot carries real consequences. The UK Modern Slavery Act 2015 requires organisations with turnover above GBP 36 million to publish annual modern slavery statements, but enforcement has been inconsistent. The Home Office's 2024 review found that 40% of statements filed by public bodies contained no specific actions taken, amounting to compliance theatre rather than genuine due diligence (Home Office, 2024). Environmental risks are equally obscured: without traceability, public buyers cannot verify carbon claims, assess deforestation risk in commodity supply chains, or confirm compliance with the UK Environment Act's due diligence requirements for forest-risk commodities.

Greater Manchester's pilot was designed to address these gaps by building a digital traceability infrastructure that could be replicated across other combined authorities, metropolitan boroughs, and utility providers.

Key Concepts

Multi-tier mapping refers to the process of identifying suppliers beyond the direct contractual relationship, tracing materials and components through Tier 2 (suppliers' suppliers), Tier 3, and in some cases Tier 4 or deeper. The GMCA pilot required mapping to at least Tier 3 for high-risk categories including textiles, electronics, food services, and construction materials.

Digital product passports (DPPs) are electronic records that travel with a product or material, containing verifiable information about origin, composition, certifications, and chain of custody. The GMCA pilot used DPPs for construction materials procured under the region's GBP 2.4 billion housing retrofit programme.

Risk-based due diligence prioritises traceability effort on categories and geographies with the highest probability of human rights, environmental, or governance violations. The pilot used a risk matrix combining country-level Modern Slavery Index scores, sector-specific risk assessments from the Gangmasters and Labour Abuse Authority, and environmental impact data from the DEFRA input-output model.

Interoperability is the ability of different traceability systems to exchange data seamlessly. The GMCA pilot adopted the GS1 EPCIS 2.0 standard for event-level supply chain data, enabling integration with existing enterprise resource planning (ERP) systems used by suppliers of varying sizes.

What's Working

The GMCA Supply Chain Transparency Programme

The programme launched in January 2023 with a 12-month pilot covering four procurement categories: uniforms and workwear (GBP 8 million annually), food and catering services (GBP 22 million), construction materials for social housing (GBP 45 million), and IT hardware (GBP 14 million). These categories were selected based on spend volume, known supply chain risks, and availability of willing Tier 1 suppliers.

The technical backbone was a cloud-based platform developed by UK-based traceability firm Segura Systems, which aggregated supplier self-reported data, third-party audit results, and open-source risk intelligence. Suppliers were required to register on the platform, disclose their own supplier lists, and provide evidence of due diligence for each sub-tier. The platform cross-referenced disclosed supplier locations against databases including the US Department of Labor's List of Goods Produced by Child Labor, the Walk Free Foundation's Global Slavery Index, and CDP environmental disclosure data.

Within the first 12 months, the programme achieved Tier 2 visibility for 89% of spend in pilot categories and Tier 3 visibility for 54%. The workwear category yielded the most dramatic findings: mapping revealed that 4 of 11 uniform suppliers sourced cotton from spinning mills in Tamil Nadu, India, where the Sumangali scheme (a form of bonded labour targeting young women) remains prevalent despite industry pledges to eliminate it. Two suppliers were unable to demonstrate adequate due diligence and were placed on corrective action plans with 90-day remediation timelines.

Thames Water Utility Traceability Initiative

Thames Water, the UK's largest water and wastewater utility serving 15 million customers, piloted a supply chain traceability programme in 2024 covering its GBP 1.8 billion annual capital expenditure on pipes, pumps, treatment chemicals, and construction services. The utility adopted a phased approach, beginning with chemicals procurement (GBP 280 million annually) where supply chain concentration risk was highest.

The pilot discovered that 73% of the polyaluminium chloride (PAC) used across Thames Water's 350 treatment works originated from a single refinery complex in China's Shandong province, creating both supply security and environmental compliance risks. The refinery had received three environmental violations from China's Ministry of Ecology and Environment in the preceding 18 months. Thames Water subsequently diversified its PAC sourcing to include European manufacturers, reducing single-source concentration to 41% and achieving a 15% reduction in Scope 3 emissions from chemicals procurement through shorter supply chains (Thames Water, 2025).

Bristol City Council's Ethical Procurement Tracker

Bristol City Council integrated supply chain traceability into its Social Value procurement framework in 2023, requiring all contracts above GBP 100,000 to include traceability provisions scored as part of the quality evaluation (weighted at 10% of total score). The council partnered with the University of Bristol's Centre for Business, Organisations and Society to develop a supplier traceability maturity model with five levels, from basic Tier 1 disclosure to full multi-tier digital traceability with third-party verification.

After 18 months, 82% of new contracts above the threshold included traceability commitments, and 34% of suppliers had progressed at least one maturity level. The programme identified GBP 3.2 million in annual savings through consolidated sourcing decisions enabled by better supply chain visibility, where duplicate suppliers at different tiers were discovered and procurement was rationalised (Bristol City Council, 2025).

What's Not Working

SME supplier burden remains the most persistent challenge. In the GMCA pilot, suppliers with fewer than 50 employees took an average of 34 hours to complete initial platform registration and sub-tier disclosure, compared with 8 hours for large enterprises with existing supply chain management systems. Dropout rates among SME suppliers reached 22% in the first six months, with many citing the administrative burden as disproportionate to contract values. The GMCA responded by introducing a simplified disclosure template for contracts below GBP 500,000 and funding a dedicated supplier support helpline, reducing the SME dropout rate to 11% by the end of year two.

Data verification gaps undermine confidence in supplier-reported information. An independent audit of GMCA platform data conducted by Achilles Information found that 28% of supplier self-reported sub-tier information contained material inaccuracies, including incorrect facility addresses, outdated certification status, and missing sub-suppliers. Without ground-truthing through physical audits or satellite verification, the traceability system risks becoming a digital equivalent of the paper-based compliance systems it was designed to replace.

Interoperability failures between traceability platforms create fragmentation. Suppliers participating in both the GMCA programme and separate traceability requirements from private sector customers (such as Marks and Spencer's Plan A or Tesco's supply chain transparency initiative) reported maintaining data in three to five separate systems with no automated data sharing. The absence of a UK-wide public sector traceability standard means each council or authority designs its own requirements, multiplying supplier compliance costs without proportional transparency gains.

Political and budget cycles threaten programme continuity. The GMCA programme received GBP 2.1 million in initial funding from the UK Shared Prosperity Fund, but ongoing operational costs of approximately GBP 450,000 per year require dedicated budget allocation. Changes in political leadership following the May 2024 local elections introduced uncertainty about continued funding, with the programme ultimately secured for an additional two years but with a 20% budget reduction that forced cuts to the supplier support function.

Key Players

Established organisations: Segura Systems (UK traceability platform provider powering the GMCA pilot), Achilles Information (supply chain risk and compliance verification), GS1 UK (standards body for supply chain data interoperability), Sedex (ethical supply chain data platform with 85,000 member companies), CIPS (Chartered Institute of Procurement and Supply, providing procurement capability frameworks)

Startups: Provenance (London-based supply chain transparency platform using blockchain-anchored claims), Altana AI (supply chain mapping using trade data and AI, expanding into UK public sector), Sourcemap (end-to-end supply chain mapping with risk analytics), TrusTrace (fashion and textiles traceability platform adopted by several UK councils for uniform procurement)

Investors and funders: UK Shared Prosperity Fund (initial GMCA programme funding), Innovate UK (co-funded Bristol Council's traceability pilot through the Sustainable Innovation Fund), British International Investment (supporting supply chain transparency in developing country suppliers linked to UK public procurement)

Action Checklist

• Conduct a spend analysis to identify the top 10 procurement categories by value and map known supply chain risks using DEFRA's input-output model and the Global Slavery Index
• Select 3 to 4 pilot categories based on spend volume, risk profile, and availability of engaged Tier 1 suppliers willing to participate
• Adopt an interoperable data standard (GS1 EPCIS 2.0 or Open Supply Hub) to avoid vendor lock-in and reduce supplier data entry burden
• Build simplified disclosure requirements for SME suppliers with fewer than 50 employees, limiting initial requests to Tier 2 mapping and basic certification evidence
• Integrate traceability requirements into procurement scoring frameworks, weighting at 5 to 10% of quality evaluation to incentivise supplier participation without excluding smaller bidders
• Commission independent data verification audits at 6-month intervals, targeting a minimum 20% sample of supplier-reported sub-tier information
• Establish a dedicated supplier support function (helpline and onboarding workshops) budgeted at approximately GBP 50,000 to GBP 100,000 per year depending on programme scale
• Secure multi-year budget commitments (minimum 3 years) to provide programme continuity beyond political cycles and build supplier confidence in sustained requirements
• Publish anonymised programme results annually to build the evidence base for supply chain traceability effectiveness and support replication by other authorities

FAQ

Q: How much does it cost to implement a municipal supply chain traceability programme? A: Based on the GMCA and Bristol pilots, initial setup costs range from GBP 500,000 to GBP 2.5 million depending on the number of procurement categories, chosen technology platform, and level of supplier support provided. Ongoing annual costs are typically GBP 300,000 to GBP 600,000 for a combined authority covering GBP 500 million or more in annual procurement spend. However, both pilots demonstrated measurable cost savings (9% in GMCA, GBP 3.2 million annually in Bristol) through improved supply chain visibility enabling procurement rationalisation, suggesting a payback period of 18 to 36 months.

Q: What is the minimum viable scope for a traceability pilot? A: Start with 2 to 3 procurement categories where Tier 1 suppliers are concentrated (fewer than 20 suppliers covering 80% or more of category spend) and where supply chain risks are well documented. Uniforms and workwear, food and catering, and cleaning services are common starting points for UK councils because they combine relatively simple supply chains with well-established risk profiles for labour exploitation. Avoid starting with construction or IT hardware, which involve highly complex, multi-layered supply chains that can overwhelm early-stage programme capacity.

Q: How do we handle suppliers who refuse to participate in traceability requirements? A: The GMCA pilot adopted a graduated approach. For existing contracts, traceability requirements were introduced through contract variation with a 12-month transition period. Suppliers who declined to participate were not immediately excluded but were flagged for enhanced due diligence using open-source intelligence and third-party risk databases. For new procurements, traceability became a scored element of tender evaluation, meaning non-participating suppliers were not excluded but scored lower. Only 3% of suppliers in pilot categories ultimately declined to participate when the requirement was framed as a scored criterion rather than a pass-fail gate.

Q: What data protection considerations apply to supply chain traceability in the public sector? A: UK GDPR applies to any personal data collected through traceability systems, including individual worker data in labour rights due diligence. The GMCA programme conducted a Data Protection Impact Assessment (DPIA) before launch and adopted a data minimisation approach: supplier facility locations and certification data were collected at the organisation level, while individual worker-level data (such as wage records or working hours) was retained only by audit firms operating under separate data processing agreements. All data was stored on UK-hosted servers with ISO 27001-certified cloud providers, and supplier data was not shared between participating councils without explicit consent.

Q: Can blockchain add value to municipal supply chain traceability? A: The GMCA pilot evaluated blockchain-based solutions during its technology selection phase and concluded that for public sector traceability at the current maturity level, the incremental benefits of blockchain (immutability, decentralised trust) did not justify the additional complexity and cost. The pilot found that the primary challenge was data collection and verification, not data integrity after collection. Provenance, a blockchain-anchored traceability provider, was used in a limited sub-pilot for construction timber chain of custody, where it demonstrated value in providing tamper-evident certification records, but the broader programme relied on conventional cloud-based platforms with role-based access controls and audit trails.

Sources

• Local Government Association. (2025). National Procurement Strategy for Local Government: Annual Review 2024-25. London: LGA.
• Chartered Institute of Procurement and Supply. (2024). Supply Chain Visibility in UK Public Procurement: Survey Results and Benchmarking. Stamford: CIPS.
• Home Office. (2024). Review of the Modern Slavery Act 2015: Public Sector Compliance Assessment. London: HM Government.
• Greater Manchester Combined Authority. (2025). Supply Chain Transparency Programme: Two-Year Impact Report. Manchester: GMCA.
• Thames Water. (2025). Responsible Procurement Report 2024-25: Supply Chain Traceability and Risk Management. Reading: Thames Water Utilities Ltd.
• Bristol City Council. (2025). Ethical Procurement and Social Value: Annual Progress Report. Bristol: Bristol City Council.
• Achilles Information. (2025). Supply Chain Data Quality in Public Sector Traceability Programmes: Independent Audit Findings. Abingdon: Achilles Information Ltd.
• GS1 UK. (2025). EPCIS 2.0 Implementation Guide for Public Sector Supply Chain Transparency. London: GS1 UK.