Superdry is cutting about one in five jobs at its head office as the struggling fashion brand resists the return of co-founder Julian Dunkerton to steer the business.

The company confirmed it had begun a consultation with staff at its Cheltenham headquarters, where it has about 1,000 staff, which could result in up to 200 job losses as part of a wider plan to cut running costs by £50m over the next three years.

Euan Sutherland, the Superdry chief executive, is fighting fires on several fronts. A series of profit warnings have weighed heavily on the share price which has fallen by two-thirds over the past year while the dispute with Dunkerton has become increasingly acrimonious. On Friday the entrepreneur, who stepped back a year ago from the business he co-founded in 2003, confirmed he was forcing an extraordinary meeting to return as a non-executive director.

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Superdry said the cost-cutting plan, first reported by the Evening Standard, had been flagged at its half-year sales update in December when it blamed unseasonal temperatures for disappointing sales of its hoodies and winter jackets. At that time the company said it was also looking to save money by closing or downsizing stores and seeking rent reductions.

“We have embarked on a cost transformation programme,” said a spokeswoman for Superdry. “As part of that, we have started a process of consultation with colleagues about how it will impact our central head office functions.”

Superdry’s deteriorating financial performance has seen Dunkerton demand to return. The collapse in the company’s market value means it will be relegated from the FTSE 250 to the FTSE All-Share Index when the reshuffle takes place later this month. Its decline has had a substantial impact on Dunkerton’s personal fortune. The shares were worth £20.39 at the start of 2018 but are now changing hands for £5.54, wiping more than £220m off the value of his 18.5% holding.

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Last year Dunkerton told the Guardian the management team were “out of their depth”. “In the top team there is nobody with clothing or brand experience, and that’s a major issue,” he said.

Superdry is now obliged to hold an extraordinary meeting this month to consider Dunkerton’s plan which also involves installing Peter Williams, who is the chairman of online fashion retailer Boohoo, as a non-executive director.

But the company argued that Dunkerton was part of the company’s problem. “The board believes that Mr Dunkerton’s views on the strategic direction of the group are directly at odds with the unanimous views of the management team and the board and therefore his return to the business would be counter-productive and highly disruptive,” the company said on Friday.