Sainsbury's boss Justin King to step down in July

Sainsbury's has said its chief executive Justin King is to leave the supermarket chain in July, after 10 years at the head of the company.

Mike Coupe, Sainsbury's group commercial director, will succeed him as chief executive, the company said.

Sainsbury's chairman David Tyler said Mr King was "a truly exceptional leader", adding that he leaves "a lasting legacy".

Mr King said leading the company had been a "privilege".

"This was not an easy decision for me to make, and in truth it will never feel like the right time to leave a company like Sainsbury's," he said.

Mr King told the BBC that a good leader "goes when people are still screaming out for more".

He added that it was the "right time for me, and for the company, to go". Mr King said that he hoped history would judge him "to be a great leader", and that in one word, being a chief executive was "relentless".

Mr King will leave Sainsbury's after its annual general meeting on 9 July.

'Top performer'

Retail analyst Richard Perks told the BBC that Mr King had done "fantastic" things at Sainsbury's.

"He's transformed the business into a top performer - in its sector it is market leader at the moment," he said.

Mr Perks added that Mr King had expanded the company into non-food items, and successfully developed Sainsbury's Local branches.

Regarding the challenge facing Mr King's successor Mr Coupe, Richard Perks said that his task was "huge".

"We have to hope that Mike Coupe can fill those big shoes, but we probably won't know how he's really doing for two-to-three years".

Sainsbury's has expanded into non-food offerings under Mr King

Douglas McNeill, investment director at the stockbrokers Charles Stanley, said that although Mr King was leaving the company in much better shape than others in the supermarket sector, the impact on the brand would not be overly significant. "Customers care about price not the man at the top," he said.

"We have to be wary of subscribing to the cult of chief executive. Business is a team game and chief executives are only one element in the mix of a management team, and the new man is well known to a City audience."

However, Mr McNeill said that Mr King would be regarded as a success - and that some of his strategic decisions, such as sticking to the UK market, had been beneficial to the company.

"He's kept Sainsbury's a simpler business. Others - such as Tesco - have tried to make it overseas and it has caused problems."

Sainsbury's said that under Mr King, sales had risen by a total of £9.5bn, while underlying profits had risen from £254m in 2004-05 to £756m in 2012-13.

The supermarket chain, which has a 17% share of the UK's grocery market, is now worth about £6.8bn on the stock market.

Sainsbury's share price hit a peak of about 600p in June 2007, but is now trading at around 346p, despite five consecutive years of profit growth.

Shares in the supermarket closed down more than 2% on the news of Mr King's departure.

Different ranges catering to different types of customer needs have proved popular

Where next?

Speaking to the BBC, Mr King was asked if he would consider the role of boss of Formula One, should it become available - something which has been speculated upon.

He said: "I'm not ruling anything out, and not ruling it in… I'm still a young man, with plenty left in the tank. When the right things comes along I'll grab it with both hands."

Mr King's successor, Mike Coupe, has been group commercial director since 2010, with responsibilities including trading, marketing, IT and the company's online offering.

He has a long career history in the food retail sector.

Prior to his role at Sainsbury's, Mr Coupe was a board director of Big Food Group, and managing director of Iceland Food Stores. Before that he worked at both Asda and Tesco.