The ICAEW conducted research in March 2016, looking at the readiness of UK small business for HMRC's new Making Tax Digital initiative.
Using the survey estimate that 75% of UK small businesses do not currently use accounting software, the calculation of UK businesses that ARE using accounting software gives a figure of 1.25 million.
I struggle to get my estimates of the user numbers for Sage, QuickBooks, Xero, KashFlow et-al. to total anything near a million.
This suggests that either [a] the ICAEW percentages are not accurate or [b] there is an unknown, invisible accounting software provider making up the difference between the visible software companies and the total.
A bit like "Dark Matter" in the universe?