The chief executive of C&C Group, who are the owners of Tennent's, has stepped down.

Beer and cider maker C&C has announced its boss will be stepping down after just one year at the helm, after overseeing accounting errors during a botched software upgrade which cost it millions of pounds.

Patrick McMahon will leave the role immediately, having stepped up from his position as finance chief to become the group’s chief executive in May last year.

The decision came after C&C said it had found failures in the company’s accounting and that opportunities had been missed to spot and address issues.

The brewer, which makes Bulmers, Magners and Tennent’s, last year revealed it took a hit after implementing a new software system at Matthew Clark and Bibendum, a British subsidiary.

The Tennent's factory is located on Duke Street in the city's East End.

On Friday, it said the issues had cost it 17 million euros (£14.5 million) worth of adjustments to profits in previous years, and that there “will clearly be an impact” to its finances over the latest year.

Mr McMahon “acknowledges that the relevant shortcomings occurred at a time when he had overall responsibility for the group’s finance function”, and it is therefore “in the best interests of the group” for him to step down, C&C said.

C&C’s chairman and the former boss of pub group Marston’s, Ralph Findlay, has been appointed chief executive with immediate effect.

He will remain in the role for up to a year and a half, until a permanent successor is found.

Meanwhile, C&C revealed it swung to a loss over the latest financial year.

Its statutory pre-tax loss was £111 million for the year to the end of February, from a profit of £52 million the prior year.

It also reported weaker demand for its cider brand Magners, with the volume of sales tumbling by 18% across Britain year on year.

However, the company said it was having more success from Tennent’s and Bulmers, gaining a greater share of the market in Scotland and Ireland respectively.

It also reported a 24% jump in the volume of sales of its “premium” beer brands in Britain, which include Menabrea and Heverlee.

C&C said it was anticipating a boost from the upcoming Euro football tournament, with both England and Scotland taking part.

“Whilst we remain cautious about the consumer outlook for the year, the market dynamics indicate that consumers are seeking affordable treats including visits to pubs and restaurants,” the firm said.