Since September, Mr Treger and his colleague Brian Myerson have with JO Hambro and Partners, a small investment bank, been orchestrating a campaign against the board under the leadership of the 70-year old Mr Stevens.
Tom Long, a non-executive director since 1991, also yesterday announced his resignation, apparently because he was unable to agree to the terms proposed for the new chairman.
Mr Wallis is to receive a basic, non-pensionable salary of pounds 100,000 and will participate in an incentive scheme which will give him up to pounds 1m if the company's share price performance matches the upper quartile of the FT-SE 250 index over the next two years. Mr Wallis was widely credited with turning round Fisons after a series of disasters under previous management, before selling out to Rhone-Poulenc Rorer last year for pounds 1.8bn and nearly tripling the share price.
Mr Treger said: "We are just very happy that after a month of prevarication the board of Scholl has bowed to the wishes of a majority of shareholders. We believe this is a victory for shareholder pressure in the UK and are very pleased that someone of [Mr Wallis's] calibre is coming on board."
Mr Wallis said he had been approached by the rebel group six to eight weeks ago, but had had very little contact with them since. He had made clear he would not take up the job without agreement to two conditions. "Firstly, unless it was understood that I wouldn't favour them above any others and secondly that a majority of the company's shareholders had to be quite clear that wanted me. It rapidly became quite clear that that was the case."
He refused to elaborate on any plans for the business before embarking on a world tour of the operations over the next four the six weeks in the company of Colin Brown, chief executive. "Obviously I have got one or two ideas, but I don't want to formulate those from outside until I have been around and seen one or two businesses from inside."
He suggested there were unlikely to be any further board changes. Since leaving Fisons, Mr Wallis has taken on the chairmanship of LLP, owners of Lloyds of London Press, and Sheffield Forgemasters.