I remember when Japan did it in the early 90s. Suddenly, without warning, at dawn, Little Teheran near Ueno was surrounded by shoulder-to-shoulder police officers. None escaped. Detained. Processed. No visa, or expired visa, out!
By evening, rape, robberies, burglaries, assaults, murders and ALL other crimes had receded back to non-existent levels.
Gone and never allowed back in..EVER!
Of course, an island is easier to police. Same situation, though. Started out as virtue signaling on a national level to conform with global group think. Then, the voters got fed up and started making waves.
Last I looked the UK is one island and part of another.