* Julian Dunkerton reappointed a director
* Margin of victory is slender
* Incumbent directors could resign (Adds detail after final count, analyst comment, updates shares)
April 2 (Reuters) - The co-founder and former boss of Superdry, Julian Dunkerton, is to return to the board of the British fashion group after narrowly winning the support of shareholders - a development which could prompt the chief executive to quit.
Needing a simple majority of votes cast at a general meeting of investors to be re-appointed as a non-executive director, Dunkerton secured 51.15 percent.
Shares in Superdry, already down 64 percent over the last year, lost a further 5.7 percent by 1345 GMT, valuing the business at around 423 million pounds ($551 million).
Dunkerton, who owns 18.4 percent of the equity, quit the firm a year ago after a row over strategy. He takes issue in particular with Superdry's product design and internet plans.
He was backed by the firm's co-founder and former brand and design director James Holder, who has a 9.7 percent stake.
"I can't wait to get started," Dunkerton said in a statement.
Superdry, whose main products are sweatshirts, hoodies and jackets, has issued several profit warnings, the latest in December. It has been led by Chief Executive Euan Sutherland, a former boss of the Co-op, since 2014.
Analysts at Peel Hunt said Sutherland "is almost certain to leave."
"The immediate impact of (Dunkerton's) return is likely to be additional costs as he rebalances the business and seeks to reinvigorate the product," they said.
BOARD TO MEET
Superdry's board had opposed Dunkerton's combeack, saying it would be damaging and disruptive. It had also indicated that Dunkerton's return would see directors either resign or not seek re-election.
The firm said its board, including Dunkerton, will meet immediately "to assist this process of change."
"Whilst the board was unanimous in its view that the resolutions should be rejected and 74 percent of shareholders other than Julian and James have voted against, there was a narrow overall majority in favor and we accept that outcome," said Chairman Peter Bamford.
Dunkerton has been accused by Superdry's board of a lack of transparency with shareholders.
His reappointment was as a non-executive director, requiring the support of 50 percent of voting shareholders. However, the board said he had told them he wants an executive role responsible for product, brand and marketing, which would have required over 75 percent support.
Superdry's shareholders also supported the appointment of Peter Williams, an industry veteran who is the current chairman of online fashion retailer Boohoo, on to the board as a non-executive director. Williams also won the support of 51.15 percent of votes cast.
His appointment was also opposed by the Superdry board, which said he could not be considered independent as he represents the interests of Dunkerton and Holder. ($1 = 0.7670 pounds)
(Reporting by James Davey in London and Noor Zainab Hussain in Bengaluru; Editing by Arun Koyyur/Keith Weir)