I suggest - read the prospectus..17 Feb 2014 23:11
..at least as a starting point - for an idea about how the different divisions contribute to turnover / profit see part 11 (p.70) - this information is based on the audited accounts!
As per the latest RNS: "Preliminary results for the year ended 31 December 2013 will be announced on 12 March 2014" and so some validation of the prospectus should be possible. As for MSmith's comments about legacy code, presumably all real-world systems, actually in use, have it. Difficult to see how they've made a profit if there were that much of a maintenance headache!
Still, one to watch IMO etc.
BTW you can find the prospectus at http://www.servelec-group.com/Investors/Servelec%20Group%20plc%20Prospectus.pdf