Police Reform Act 2002 s50
(1) If a constable in uniform has reason to believe that a person has been acting, or is acting, in an anti-social manner (within the meaning of section 1 of the Crime and Disorder Act 1998 (c. 37) (anti-social behaviour orders)), he may require that person to give his name and address to the constable.
(2) Any person who
(a)fails to give his name and address when required to do so under subsection (1), or
(b)gives a false or inaccurate name or address in response to a requirement under that subsection,is guilty of an offence and shall be liable, on summary conviction, to a fine not exceeding level 3 on the standard scale.