Have you tried looking in army surplus stores?
I've seen Ex-military and police coats similar to that in several (though you may need to be prepared to pay a little bit).
Since your profile says chesterfiled, could you get to into nottingham? theres a huge one I've forgotton the name of just outside the city center; and theres bound to be ones local, checking the yellow pages is a good idea.
Up and coming
Saber full armour (fate/stay night)
Utsuho Reiuzi (Touhou Project)
London Expo May 2010
J-Culture Con 2010