Finance director Jonathan Houlton said that the results were thanks to focusing on framework deals. The privately owned contractor's long-term clients include retailers Boots, Marks & Spencer and Waitrose.
Houlton added that he expected the construction division to increase its turnover from £526m in 2003 to between £575m and £580m this year.
The residential development business is expected to post poorer results this year as it leaves the executive homes market and invests heavily in regeneration and lower end of the market schemes.
It has conducted initial interviews with the shortlisted candidates but is unlikely to announce Robertson's successor until the autumn. Candidates are understood to have been drawn from inside and outside the company.