49. Altodigital

Key points

Revenue: £71.2m (+10%)

Net profit: 0.6%

Staff: 492

Hampshire-based OneCom claims it is Vodafone's largest enterprise partner, managing 325,000 mobile connections. Revenue rose 19 per cent in its year to 31 December 2017 thanks to a mixture of organic growth and its hiving up of recent acquisition, fellow Vodafone partner Evolve Telecom. However, it admitted that the EU's abolition of roaming charges hit its bottom line as net profits shrank from £7.5m to £4.6m.