The decision ends a two-month tug-of-war between the companies vying for his talents.
Lewis said: “My reasons for leaving are clear. There are not the opportunities within Schal for me to grow. Mace has big projects, but my role there will allow me to do other things, such as cultivating a client base. That simply wasn’t possible at Schal.” Lewis added that he would be entitled to take up share options at Mace.
Lewis confirmed that there was unease at Schal because of the delay in appointing a successor to managing director Malcolm Bairstow.
He said: “There is uncertainty at the company and that does worry a lot of people. If Schal doesn’t sort out the situation with Malcolm’s successor, it will lead to a loss of confidence with clients, as well as staff.
“But my reasons for leaving are not connected to the situation with Malcolm. It’s purely that better opportunities are available for me with Mace.”
Lewis, who has been with Schal for three-and-a-half years, had worked with Mace previously and is well-respected in the industry as a project director.
Lewis decided to leave despite an attempt to persuade him to stay by Sir Neville Simms, deputy chairman and chief executive of Schal parent Carillion, and executive director John Sharples.
He said he had been offered a position as operations director in Carillion’s special projects division. “Potentially, we were looking at an operations director role within Carillion’s special projects division,” said Lewis, “but in the end, I have chosen to go with Mace.”