2. A person falls within this paragraph if he has been convicted of any of the following offences against a child committed at the age of 18 or over or has been cautioned by a constable in respect of any such offence which, at the time the caution was given, he admitted—
(a)an offence under section 2 or 3 of the Sexual Offences Act 1956 Act (procurement of woman by threats or false pretences);
(b)an offence under section 4 of that Act (administering drugs to obtain or facilitate intercourse);
(c)an offence under section 14 or 15 of that Act (indecent assault);
(d)an offence under section 16 of that Act (assault with intent to commit buggery);
(e)an offence under section 17 of that Act (abduction of woman by force or for the sake of her property);
(f)an offence under section 24 of that Act (detention of woman in brothel or other premises).