Sir: The horsemeat scandal shows the time has come for supermarkets to map out their shared supply chain. It took four weeks to establish which retailers had purchased horsemeat because they only understood their own arrangements - with no visibility of whether rivals were using the same supplier.

We need a step change. If supermarkets worked together to map out their supply chains, they could identify and manage the full spectrum of risk - including health and safety, compliance, CSR and ethics.

They could see where they are reliant on the same suppliers and make contingency plans. They could also standardise the pre-qualification and evaluation of suppliers, and organise audits for any supplier deemed to be high-risk. A truly collaborative approach would give everyone renewed confidence in the integrity of supplier information.

Adrian Chamberlain, CEO, Achilles