LONDON (Reuters) – Tesco, Britain’s biggest retailer, said on Monday it would no longer operate stores under the low-cost “Jack’s” brand, less than five years after it established the format amid much fanfare. The group launched Jack’s, named after Tesco’s founder Jack Cohen, in 2018 at a store in Chatteris, eastern England, as part of its centenary celebrations. Taking on German-owned discounters Aldi and Lidl, the store focused on simplicity and own-brands to keep costs and prices down. But expansion of the format has been slow. Tesco said of the 13 Jack’s stores, six will be converted to Te…