98. Charterhouse

Revenue: £44.7m (+87%)

Staff: 241

Charterhouse made five bolt-on acquisitions in its extended 16-month year to 31 March 2021, labelling it a "transformational period" as revenues swelled to £59.6m (an 87 per cent pro-rated rise) and it moved beyond its UC roots into networking and security. In June 2022, the August Equity-backed outfit said it was on course to be the first UK partner of Extreme Networks to do $10m of business with the networking vendor in a single financial year. It also partners with the likes of 8x8, Mitel, Palo Alto and Virtual1.