16. Bytes - £160m

The software licensing and managed print specialist added to its top line and its skills roster with the acquisition of Security Partnerships in summer 2011. During its first year under new ownership, the Surrey-based security VAR increased its top and bottom lines by more than 20 per cent year on year. Revenue was up to £10.1m, while pre-tax earnings spiked to £1.5m. The firm, which has remained an autonomous operating unit, adds to Bytes’ existing turnover of around the £150m mark.

Key software vendor partners include Adobe, Oracle, Citrix and VMware, while RSA, Symantec, Websense and Check Point are among the firm’s security alliances. Xerox is the printing partner of note. Bytes is part of the £2bn South African giant Altron Group, which operates across the worlds of IT, telecoms and electronics.