From the Sexual Offences Act 2003
>>>3 Sexual assault
(1) A person (A) commits an offence if-
(a) he intentionally touches another person (B),
(b) the touching is sexual,
(c) B does not consent to the touching, and
(d) A does not reasonably believe that B consents.
(2) Whether a belief is reasonable is to be determined having regard to all the circumstances, including any steps A has taken to ascertain whether B consents.
(3) Sections 75 and 76 apply to an offence under this section.
(4) A person guilty of an offence under this section is liable-
(a) on summary conviction, to imprisonment for a term not exceeding 6 months or a fine not exceeding the statutory maximum or both;
(b) on conviction on indictment, to imprisonment for a term not exceeding 10 years. <<<
As far as I am concerned if I give a permission to a security person to physically search me I am not reasonably expecting that search to include a search of my genitals. If that person is doing it delibrately and not accidently then it must be sexually motivated. If it happens to me I am calling the police. It may be difficult to prove and may go nowhere but that is not my problem. My duty is to report the crime.