Sexual Activity With a Child

A Sex offender who has been convicted of Sexual activity with a child is
(1)A person aged 18 or over (A) commits an offence if—
(a)he intentionally touches another person (B),
(b)the touching is sexual, and
(c)either—
(i)B is under 16 and A does not reasonably believe that B is 16 or over, or
(ii)B is under 13.
(2)A person guilty of an offence under this section, if the touching involved—
(a)penetration of B’s anus or vagina with a part of A’s body or anything else,
(b)penetration of B’s mouth with A’s penis,
(c)penetration of A’s anus or vagina with a part of B’s body, or
(d)penetration of A’s mouth with B’s penis,
is liable, on conviction on indictment, to imprisonment for a term not exceeding 14 years.
https://www.legislation.gov.uk/ukpga/2003/42/part/1/crossheading/child-sex-offences
UK sex offenders and Foreign Nationals who have been convicted with Sexual activity with a child.