Stuart Mitchell has stepped down as CEO of Wilkinson after six years.

The company, which tops The Grocer’s ranking of the UK’s Top 50 independent grocery retailers, said Mitchell was leaving to pursue “other opportunities” - although it is unclear what he is planning.

Mitchell has led Wilkinson through a massive period of expansion since taking control in 2006. He grew the store estate from 273 to 367 stores, introduced catalogues and in-store order points, rebranded two thirds of the estate and launched an e-commerce website, including mobile ordering.

The former Sainsbury’s MD also hired a number of colleagues from the world of grocery, including Asda veteran Peter Pritchard as head of buying, and opened an office in Hong Kong dedicated to sourcing products.

“Stuart’s contribution to Wilkinsons in almost six years as CEO has been extraordinarily valuable and he will be missed for his larger-than-life personality, good nature and energy,” the company said in a statement.

Wilkinson would continue to be led by the existing board and executive management team ahead of the recruitment of a new CEO, the company added.

A spokesman said there were no issues “financial or otherwise” surrounding the resignation. The business was “robust, in great shape and well-invested,” and Mitchell had taken a “personal decision to move on,” he added.

Wilkinson reported a 6.3% dip in pre-tax profits to £60.8m in the year to 28 January 2011, on sales up 0.2% to £1.56bn. Its full-year results are due in August. Mitchell left the MD role at Sainsbury’s in May 2004 after 20 years with the supermarket chain. He moved to Taiwan to become MD of Superdrug owner AS Watson’s health & beauty division, but moved back to the UK two years later.