50 GBM Digital
Revenue: £76.9m (-58%)
Net profit margin: 0.6% Staff: 55
This Apple education specialist's revenues have yoyoed in recent years, falling to £76.9m in its year to 31 December 2018 from a high of £250m in 2016. GBM Digital's website features perhaps the most impressively high-spec video case studies of any firm in the top 100. Last year it launched a retail store in the centre of its home city of Manchester under the Sync banner.