Question to the Home Office:

To ask His Majesty's Government what estimate they have made of the number of illegal immigrants residing in the UK.

By its very nature, it is not possible to know the exact number of people living in the UK illegally, or produce official estimates of that illegal population. In June 2019, the Office for National Statistics (ONS) published a note on ‘measuring illegal migration’, which can be found here: Measuring illegal migration: our current view - Office for National Statistics (ons.gov.uk).