The Kelkoo press release was based on a mystery shopping study carried out by the Centre for Retail Research and drew immediate criticism from BAA, the company that owns and operates Heathrow. BAA said the research was “misleading and incorrect”, as comparisons with prices at other European airports were invalid because of a “false exchange rate” and some of the items bought in the mystery shopping exercise were not on sale at the London airport.

BAA questioned Kelkoo about the findings, which led to a review of the study and in turn its withdrawal. In a statement Kelkoo said: “It has come to light during the course of this review that certain data from the CRR report in relation to the value of tax free discounts available at London Heathrow was innaccurate.”

It added: “Kelkoo had no way of knowing of these inaccuracies at the time when the press release was published, and relied on the report in good faith. However, Kelkoo accepts that as a direct result of this, its press release contained inaccurate statements and those statements are now withdrawn. Kelkoo has apologised to BAA, the owners of Heathrow.”

Kelkoo’s study focused on tax-free shopping for passengers travelling within the EU and involved mystery shoppers purchasing a “representative basket’ of 22 items at 10 European airports, including Heathrow, Paris, Rome and Berlin. The results claimed that shoppers at Heathrow received the worst discount – a saving of 3.1% compared to high street prices – while the savings at other airports were as much as 11.9%.

A BAA spokesperson told Research: “We have accepted Kelkoo’s apology, which greatly undermines their research and underlines the need for companies, and particularly PR people, to be more careful when criticising others.”

The Centre for Retail Research did not return calls seeking comment.