39. Proact IT - £54m

Proact IT may be a new name on this list, but the company in question is familiar to channel watchers and lower-league football fans alike. Chesterfield VAR – and long-time sponsor of the Derbyshire town’s local League 2 football team – B2Net was acquired by Swedish firm Proact just before the close of its 2011 fiscal year. The year had been a successful one, with the acquisition of Cisco partner Essant helping B2Net to post turnover growth of more than a third. Operating profit was up more than £200,000 to £655,785.