Four directors have left controversial ISP adware firm Phorm, including chairman of three months Stephen Heyer. Former Chancellor of the Exchequer Norman Lamont is among their replacements.

Heyer, a former Coca-Cola executive, was appointed non-executive chairman only in August. He replaced Ertugrul, who until then had combined the roles of chairman and CEO.

Non-executive directors David Dorman and Christopher Lawrence, and chief operating officer Virasb Vahidi have also left Phorm today. All the departees "will take this action as a result of differences with Mr Ertugrul as to the management and future direction of the company," it said in a statement.

Investment bankers Stefan Allesch-Taylor and Stephen Partridge-Hicks will take non-executive directorships. Kip Meek, the chairman of the telecoms industry lobby the Broadband Stakeholder Group, will complete Phorm's new board as another non-executive.

Ertugrul said: "I welcome Lord Lamont, Kip, Stefan and Stephen to the Board. They bring extensive experience on government, business, regulatory matters and financial markets. As we move into the next phase of our development, the priority will be to build momentum in the rollout of our strategy."

The announcement to the stock exchange is here. ®