PACE 1984 s1
(1) A constable may exercise any power
conferred by this section-
(a) in any place to which at the time when he proposes to exercise the power the
public or any section of the public has access, on payment or otherwise, as of
right or by virtue of express or implied permission, OR
(b) in any other place to which people have ready access at the time when he
proposes to exercise the power but which is NOT a dwelling.
(2) Subject to subsection (3) to (5)
below, a constable-
(a) may search-
(i) any person or vehicle;
(ii) anything which is in or on a vehicle;
for stolen or prohibited articles, any article to which subsection (8a) below
applies or any firework to which subsection (8b) below applies; AND
(b) may detain a person or vehicle for the purpose of such a search.