49. ProAv - £42.3m

The audiovisual specialist has been in operation for more than 40 years and international expansion has been a key growth driver in recent times. The company recently earned a berth on the Sunday Times International Track list of £25m-plus UK companies with the fastest-growing sales into overseas territories. Between 2009 and 2011, ProAv’s international sales nigh-on trebled to £2.2m. Blue-chip customers include BT, British Airways, Marks & Spencer, HSBC, Hilton and RBS.