20. NTT Ltd

Revenue: £180.2m (-17%)

Staff: 528

A lack of consolidated accounts makes sizing this global IT infrastructure and services giant's UK business problematic, but slightly antiquated results from NTT United Kingdom Ltd (the old Dimension Data business) show revenue of £180.2m in the year to 31 March 2021. In truth, it is much larger. Globally, Cisco, Microsoft, Palo Alto Networks and AWS partner NTT Ltd claims to turn over $10bn. In October, it was fused with sister company NTT Data to create a $30bn-revenue business dubbed NTT Data, Inc.