Leisure craft insurer Navigators & General will lose 10% of its staff when Zurich shuts down its Norwich office in September.
Market sources said that the closure was prompted by the insurer's poor results and problems within its claims handling procedures.
The source said: "Every time there is a big claim they always get hit and their results aren't particularly good."
But a Zurich spokeswoman denied the claims. She said: "This is a streamlining process. As with any prudent business, it is important that we continue to review our business operations to ensure that we meet our goals in the most cost effective and efficient way."
Richard Coleman from Woodstock Insurance Brokers is to replace the company's director, Rod Daniel, who will take up the position of development underwriting manager in Leeds.
Zurich denied that Daniel's transfer to its Leeds office had anything to do with poor performance and that it was "his personal decision to relocate to Leeds".
The fate of the other five employees in the Norwich office is still uncertain.