Russell English, managing director of insurer Trenwick, has suddenly resigned.
A statement from the insurer said that English has left to pursue other interests.
Company secretary and solicitor Joanne Merrick denied there was any link between English's departure and Trenwick's ongoing merger with LaSalle.
She said: "LaSalle only has a small operation in the UK, so I think any link between our merger with LaSalle and his departure would be purely theoretically, and unlikely in practice."
Trenwick chairman Pierre Croizat is likely to assume the role of managing director, subject to approval from regulators and the firm's board of directors.