Revenue: £71.8m (+45%)
Net profit margin: 4.4% Staff: 324
This London-based Avaya and Verint partner claims to support around 10 per cent of all UK-based contact centre agents and four per cent of the total European market. Backed by Horizon Capital, Sabio is on an acquisition frenzy, but claimed organic growth generated 17 per cent of its 45 per cent revenue growth for its year to 30 September 2018. Despite boasting a presence in France, Spain, the Netherlands, Italy, Malaysia and Singapore, the UK still generates over half of its top line.