dunnhumby launches network alliance with Tesco, B&Q, John Lewis and Waitrose

Who does the enrichment is not settled by the public record. dunnhumby supplies the alliance's media intelligence and measurement, with Kevel providing the ad-serving underneath, but the release does not say whether dunnhumby enriches B&Q, John Lewis and Waitrose transaction data itself, or confirms and aggregates audiences each retailer has already built and packages them for agencies. The retailers contribute purchase data and inventory and, per dunnhumby's own statement, "maintain control of their own media businesses"; pilots start summer 2026 and have not reached rollout.

What makes the substrate worth something to a brand like a CPG or DIY advertiser is the ability to decide which campaign to fund and which households to reach with a measurable in-store/online purchase outcome - Tesco's over-23-million-household Clubcard base plus B&Q, John Lewis and Waitrose shoppers reached through one plan rather than four separate contracts.

What crosses to the brand buyer is reach against audiences and closed-loop measurement reports; the row-level Clubcard, B&Q, John Lewis and Waitrose customer data does not cross - it is activated inside the alliance platform, which is the retailers' stated condition of participation. Between the retailers, dunnhumby and Kevel the public release does not disclose data-sharing terms, so what crosses between alliance members is not settled by the sources.

Not determinable from the June 2026 announcement. The deal is at pilot stage with no pricing, revenue share or committed inventory disclosed, so whether non-Tesco retailers are leaving value on the table by routing demand through a Tesco subsidiary rather than their own networks cannot be read from the public facts.