>>gambit+(OP)
Not just the UK. In about 30 of the United States of America the age of consent is 16 [1]. Beyond that marriage is permitted with a note from parents of the minor and approval from a judge
up to 1 or 2 years below the AoC depending on the state.
[1] - https://en.wikipedia.org/wiki/Age_of_consent_in_North_Americ...