In a shock announcement to the London stock exchange Bridget McIntrye steps down as RSA UK chief executive.

See analysis: All change at RSA

RSA UK chief operating officer Adrian Brown will take over the reins as UK chief executive after it was announced this week that Bridget McIntyre is to step down.

McIntyre’s resignation came as a surprise to the market and comes amid intense speculation about the future of the insurance company.

The City’s dealing rooms are awash with rumours that the insurer, which recently posted strong interim results, could be an acquisition target.

Shares in RSA rose over 12% this week with talk that Zurich could be preparing to make a bid. The stock reached a six-month high of 163.70p on Tuesday.

Andy Haste, RSA group chief executive, who is highly regarded in the City for his efforts in reversing the fortunes of the insurer, has also been tipped as a candidate to lead a major bank.

A market source said: “RSA will look to be tough in the market place in the coming months. This might weaken their position. The timing is poor bearing in mind all the talk at the moment is about pushing up rates and brokers commissions.”

Another broker source said: “It is a real surprise considering she has only been there three years. It is a big loss to brokers as RSA had been bucking the trend in terms of pushing the rates up.”

In a statement to the London Stock Exchange on Tuesday, RSA said: "Bridget has been with the group for almost three years and has made a significant contribution to the UK business.

Bridget wants to spend more time with her family in Suffolk and she and the group board agreed that it is the right time for new leadership to take the business forward.

"Bridget will commence handover of her UK CEO responsibilities straight away but will remain on the group board until the end of the year to ensure a smooth transition."

Brown has been the UK chief operating officer since 2006. He was previously responsible for establishing the UK's direct business, More Th>n, which he ran for two years before becoming the UK director for personal lines in 2003.

Haste said: "I would like to thank Bridget for the dedication she's brought to advancing the UK business."