Lomax's twin-roles of chairman and chief executive breached City guidelines and Misys had planned to separate the roles when Lomax steps aside to become non-executive chairman in 2008.

But in September some shareholders, angered with the vendor's recent poor performance, called for Lomax to step down as chairman as early as next year and for the appointment of a new, independent chair.

In today's statement to the stock exchange, Misys says Dominic Cadbury, currently senior independent director, has been appointed non-executive chairman with immediate effect. Lomax will continue as chief executive of the company.

Misys says it will shortly begin the search for Cadbury's long-term successor as non-executive chairman, a process which is expected to take some months.

Earlier this year the Association of British Insurers (ABI), whose members control about a fifth of the UK stock market, called a meeting with Lomax and Cadbury to discuss Misys' recent profit warning and the company's search for a new chief executive.

Investors were also angered by Misys' controversial bonus retention plan, which the vendor was forced to ditch. Under the proposed scheme Ivan Martin, head of Misys' banking division, and Tom Skelton, head of the firm's healthcare division, would have received a bonus of £1.2m each to to prevent them from leaving the firm if they are not selected to succeed Lomax.

As a consequence of the board changes at Misys, John Ormerod will serve as both senior independent director and audit committee chair. The board has also appointed John King as a non-executive director with immediate effect.

In today's statement Misys also says it is still trying to find a buyer for its Sesame busines - which has been on the market since last year. The vendors maintains that the sale process in underway and an information memorandum on the business has recently been issued to interested parties.