Supermarket giant Tesco has appointed John Allan as its new chairman to replace Richard Broadbent who resigned following an accounting scandal last October.Allan, the former Deutsche Post exec who currently works as chairman at Dixons Carphone, Barratt Developments and Worldpay and as a non-executive director at Royal Mail, will join the grocery group on 1 March."I am delighted that John has agreed to join us and take on the role of chairman of the board," Broadbent said."I am sure that his wide expertise, his experience and his personal qualities will contribute greatly to the future of the group."Allan, who will be paid £650,000 per annum fixed for three years, will step down from his other roles at Dixons Carphone and Royal Mail.He said: "I'm very pleased to be taking on this role at such a critical moment for the business and look forward to working with the new executive team and the board."Comments from independent retail analyst Nick Bubb reflected the surprise in the City that Archie Norman, the man who turned around Asda in the 1990s and current ITV chairman, was overlooked for the role despite being hotly tipped for the appointment."Well, John Allan's time at the defunct supermarket chain Fine Fare in the 1980s doesn't make him a retail heavyweight like Archie Norman, but he seems to be a shrewd operator and knows his way around the boardroom, given his considerable experience, so he should be a safe pair of hands as chairman of Tesco."Shore Capital's retail analysts added that Allan has a distinguished past but "in truth we know relatively little about him"."Allan's turnaround experience may be highly valuable to Tesco and whilst not necessarily the centre of his time, he may have beneficial insights into logistics progress too."