Hi there
the only place in Wolverhampton i can think of that deals with this type of memorabilia is a small place called Mike's Militaria.

it is only a small shop on the second floor of a place called Collectors corner. The owner Mike is a extreamly nice chap, trust me i'm a bit of a regular in there and he knows his stuff.

any way he sells a lot of old military gear but also has some police gear in there, i'm sure he could help.

i can think of one more place but it's in bridgnorth.
if you can get up there it's called english herritage, its an antique centre but he has alot of police gear,well he did when i went in. the owner is a very interesting man full of knowlage i'm sure he could help.

i have attached the addresses of both shops below.
if i can think of any more places i will let you know.
i hope i have been of some help (from a west mids local to another)

-seb

Mikes militaria
3 Worcester Street
City Centre, Wolverhampton
WV2 4LD

english heritage
Whitburn Street
Bridgnorth
Shropshire
WV16 4QN