The head of Marsh UK, Bruce Carnegie-Brown, is stepping down from his role in a move that has surprised the market.

Mr Carnegie-Brown has resigned from his position as head of the UK operations of Marsh & McLennan, the biggest insurance broker in the world. He will be replaced by Alex Moczarski, formerly the head of Marsh’s Latin American and Asian businesses.

Press reports have speculated that Mr Carnegie-Brown left because of a strained relationship with Michael Cherkasky, the New York-based overall chief executive of the company. However, chairman and chief executive of Marsh’s insurance operations said: There really is no mystery. It was not a matter of a clash. It was not a matter of yesterday’s man.

Other sources have attributed the move to Mr Carnegie-Brown’s desire to pursue an activity outside of Marsh.