Dido Harding, head of Sainsbury’s convenience stores, is to join TalkTalk – the soon to be demerged broadband arm of Carphone Warehouse, as chief executive.

The move will be a blow to Sainsbury’s as Harding is viewed as one of its high fliers. According to the Daily Telegraph, it is likely Carphone’s chairman John Gildersleeve would have played a key part in the appointment. He was a long standing executive at Tesco, where Harding worked before moving to Sainsbury’s.

Carphone’s retail division – Best Buy Europe – will also be headed up by a former Tesco executive, Scott Wheway. He then moved to Boots in 2004.

TalkTalk will be Britain’s biggest residential broadband provider when it demerges from the retail arm of Carphone Warehouse early next year. Harding will leave Sainsbury’s next spring.