LONDON, Sept 9 (Reuters) - British clothing and food retailer Marks & Spencer (MKS.L) has promoted its head of food, John Dixon, to its executive board, strengthening his chance of succeeding Stuart Rose as chief executive next year.

Marks & Spencer (M&S) has always said it would prefer an internal candidate to succeed Rose, and signs of recovery at the group's upmarket food business in recent months have seen some commentators identify Dixon as the most likely successor.

He faces competition from finance director Ian Dyson and head of clothing Kate Bostock, while several external candidates including Sainsbury's (SBRY.L) Justin King and Asda's (WMT.N) Andy Bond have also been tipped as possible candidates.

Rose has been under fire from some investors since 2008, when he combined the roles of chief executive and chairman against corporate governance guidelines.

Britain's biggest clothing retailer has said it would appoint a new chief executive next year and that Rose would step down as chairman by July 2011 at the latest.

Shore Capital analyst Kate Calvert said Dixon's elevation increased his chances of becoming chief executive.

An M&S spokeswoman declined to comment.

Not all analysts, however, are convinced he would be the right man for the job.

"They've thrown a lot of cash at it (the food business)," said Credit Suisse's Tony Shiret. "To my mind, he's still got a lot to prove."

Dixon is a 23-year veteran of M&S and, like Rose, joined the firm as a management trainee. Prior to becoming director of food, he was head of the group's homewares and online businesses.

M&S also announced that Steven Holliday, chief executive of Britain's biggest utility, National Grid (NG.L), would succeed Louise Patten as chair of its remuneration committee.

Patten was criticised by some investors earlier this year for approving an executive share bonus scheme which they considered too generous.

To appease the critics, Rose and marketing director Steve Sharp waived a third of the shares awarded to them in June.

At 1400 GMT, M&S shares were down 0.9 percent at 363.2 pence, underperforming a 1 percent rise on the UK's benchmark FTSE-100 .FTSE index.

(By James Davey and Mark Potter. Editing by Simon Jessop)