The new occasion and the limits of this analysis

On September 26, 2026, InternetRetailing published a profile of John Lewis Partnership as the operator of a connected retail media system. The article does not describe a new launch that day; it examines an established architecture in which advertising on retailer websites works alongside offsite channels and loyalty data from John Lewis and Waitrose. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026]

The principal technology step was announced on June 29, when Kevel was appointed to develop the onsite network across both websites. September 26 is therefore the date of the new industry analysis, not the start of the partnership. That distinction prevents a fresh publication from being presented as a fresh operational event. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026]

How advertising channels and purchases are connected

Kevel’s layer supports self-service campaign launch, native advertising and sponsored product placements on JohnLewis.com and Waitrose.com. John Lewis Partnership said that 60% of orders for the John Lewis brand now take place online; the figure does not cover the entire group and does not measure advertising impact by itself. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026]

For the “research online, purchase offline” journey, the system uses closed-loop reporting: exposure to onsite advertising is matched with a physical purchase, including through loyalty-card data. This broadens visibility across the customer journey, but it describes an attribution mechanism rather than experimental proof of incrementality. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026]

Epsilon operates the offsite layer, where John Lewis and Waitrose advertising can run across the open web, online video and streaming services. The new profile interprets the combination of Kevel and Epsilon as a unified customer-data strategy, although public sources describe separate products and do not disclose one consolidated report covering every channel. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [3 · John Lewis Partnership · official retail media opportunities] [4 · Epsilon · launch of the John Lewis retail media platform, July 31, 2024]

What is known about effectiveness

The sources provide no results from a specific campaign: there is no observation period, advertiser or shopper sample, media spend, comparison baseline, ROAS, incremental sales, profit, repeat purchase or retention. Claims about precise targeting and closed-loop measurement describe supplier capabilities, not demonstrated economic returns. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [4 · Epsilon · launch of the John Lewis retail media platform, July 31, 2024]

Even when an advertising exposure and a later purchase can be matched, the result is attributed revenue; it does not show whether the purchase would have occurred without the ad. Measuring incremental sales requires randomly assigned control audiences or stores, predefined outcomes and profit calculated after discounts, inventory cost, technology and campaign servicing. [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [5 · Marketing Science · field experiments on advertising measurement, 2019]

Expert commentary

John Lewis Partnership’s strongest feature is not any single ad format, but the connection between multiple shopping contexts. A department store and a grocery chain produce different purchase frequencies and occasions, while websites, stores and offsite media broaden the customer journey. This can make audiences more useful to brands, but integration alone does not guarantee consistent data or measurement quality. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [3 · John Lewis Partnership · official retail media opportunities] [4 · Epsilon · launch of the John Lewis retail media platform, July 31, 2024]

The economics should be evaluated at two levels. For the retailer, the relevant measure is advertising revenue after technology, sales and servicing costs; for the advertiser, it is incremental gross profit rather than ROAS on attributed purchases. If the network monetizes demand that already existed, its revenue can rise without a comparable increase in the brand’s sales. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [4 · Epsilon · launch of the John Lewis retail media platform, July 31, 2024]

The scientific caveat is particularly important in closed systems. A study of 15 large digital advertising field experiments found that observational estimates often failed to reproduce causal effects from randomized tests. The research did not examine John Lewis Partnership, but it explains why rich loyalty data cannot replace a control group and an incrementality test. [5 · Marketing Science · field experiments on advertising measurement, 2019]

For customers, cross-channel recognition is useful when it reduces irrelevant advertising and helps them continue a decision between website and store. The risk appears when recognition turns into excessive frequency or opaque data combination. Alongside conversion, the network should monitor complaints, personalization opt-outs, reward usage, returns and repeat purchases after a service failure. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [3 · John Lewis Partnership · official retail media opportunities]

Competitive advantage depends on relationship governance, not only inventory scale. John Lewis and Waitrose can connect infrequent big-ticket purchases with frequent grocery trips, but advertisers will need clear access rules, frequency caps and comparable reporting across onsite and offsite channels. Public materials do not yet show how consistently that coordination works in practice. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [3 · John Lewis Partnership · official retail media opportunities] [4 · Epsilon · launch of the John Lewis retail media platform, July 31, 2024]

The editorial team’s conditional forecast: over the next two to four quarters, the system will become more credible if the group publishes campaign results with test and control groups, incremental profit, the share of in-store outcomes and customer-experience metrics. In the positive scenario, more relevant advertising finances better loyalty value without increasing irritation. In the negative scenario, complex attribution creates an impression of precision while hiding cannibalization and costs. Repeat purchase, communication opt-outs and profit after all expenses are the measures to watch. [1 · InternetRetailing · profile of the connected retail media system, September 26, 2026] [2 · John Lewis Partnership · Kevel partnership, June 29, 2026] [5 · Marketing Science · field experiments on advertising measurement, 2019]

Sources

  1. InternetRetailing · profile of the connected retail media system, September 26, 2026 — The new occasion for this analysis; the article connects the onsite, offsite and omnichannel components of the strategy.
  2. John Lewis Partnership · Kevel partnership, June 29, 2026 — Primary source on onsite platform features, loyalty data, ROPO measurement and rollout stages.
  3. John Lewis Partnership · official retail media opportunities — Current primary source on channels and the use of data in media planning and measurement.
  4. Epsilon · launch of the John Lewis retail media platform, July 31, 2024 — Primary source on the offsite advertising layer and technology partnership; historical context rather than a new event.
  5. Marketing Science · field experiments on advertising measurement, 2019 — Methodological background on the difference between observational attribution and causal effect; not a study of John Lewis Partnership.