Question to the Home Office:

To ask the Secretary of State for the Home Department, how many visa applicants were refused entry to the UK due to criminal convictions in each of the last two years.

UKVI do not publish statistics detailing reasons for refusal of visa applications. With regard to criminal convictions, there are different grounds under which visa applications may be refused, see:
https://www.gov.uk/government/collections/general-grounds-for-refusal-modernised-guidance

The available information on grants and refusals of entry clearance visas, are published in the quarterly Immigration Statistics, Visas volume 1 tables vi_01_q, latest edition at: https://www.gov.uk/government/publications/immigration-statistics-year-ending-march-2019/list-of-tables