The Treasury does not make assessments of the number of people who do not have a bank account. However, in 2017, the Financial Conduct Authority published the results of the Financial Lives Survey which found that 1.3 million UK adults were unbanked, i.e. have no current account or alternative e-money account.
The Financial Lives Survey report contains further information on the characteristics of the unbanked and their preferences to have a bank account. The report analyses survey results across the four nations of the UK, the nine regions of England, and by rural and urban areas. The FCA intend to repeat the Financial Lives Survey on a regular basis in future.