68. CSI

Revenue: £63.1m (-14%)

Staff: 245

"No, we're not that CSI of crime scene investigation fame," this MML-backed IBM partner stresses on its website. It did, however, finger decreased income from customers in Covid-hit verticals such as hospitality and travel as the prime suspect for a 14 per cent calendar 2021 revenue dip. Focusing more on higher-margin, complex environments during the period enabled the London-based outfit to boost gross profit margins from 40 to 45 per cent. Clients include Domestic & General and ABP Food Group.