After only one month as chief executive of Aviva, Britain’s biggest insurer and the owner of Norwich Union, Andrew Moss has already come under fire.

Norwich Union’s decision to increase premiums by an average 10 per cent across the board earned the insurer a rebuke from the British Insurance Brokers Association, which declared the move a “knee-jerk reaction”. The insurance giant was deemed to be “cashing in” on the floods that have devastated parts of the country, using them as an excuse to raise premiums across the board.

Mr Moss, an Oxford graduate, joined Aviva as finance director in 2004, from Lloyd's, where he had been on board during the aftermath of the September 11 terrorist attacks, was appointed to the top job at Aviva earlier this year.

His appointment led to the exit of Patrick Snowball, the former head of Norwich Union, who reportedly disapproved of Mr Moss’s apparent plans to outsource operations to India.

Yesterday, announcing the company’s interim results, Mr Moss said his decision to install a new management team was the “single most important thing I have done since January”.

As part of plans to bolster the asset management arm of Aviva, Mr Moss named Alain Dromer, a former HSBC executive, as the new head of the UK fund management arm Morley.

Mr Moss, a former HSBC employee himself, also signed a lucrative bancassurance deal with the bank this year.

While Mr Moss’s appointment initially received criticism that he was “unproven” in terms of direct operational experience, analysts have since welcomed his confident style.

Yesterday he was forced to respond to losses that wiped 34 per cent off first-half profits as a direct result of storms in January and mid-year floods.

There could be more trouble ahead. Rumours persist that the company is a target for investors who may push for a break-up. As a result Mr Moss is unlikely to revisit a failed £17 billion bid for Prudential.

Since taking over as chief executive, Mr Moss has embarked on a round of internal presentations, which he shared yesterday with the media and analysts in pursuit of a One Aviva, his code for a cost-cutting strategy. He declared he had become “obsessed by clarity”.

A chartered accountant by profession, Mr Moss is married with four children and enjoys golf, rugby and gardening.