Is there a model engineering society local to you?
I can't assist, as I'm in Buxton, but you might well find someone local who would drop something off for you from their local stockholder.
Fortunately I'm close to Sheffield, so it's not a problem form me, but I know I'd be happy to pick something up on someone's behalf round here.
My preferred supplier list metric BDMS rounds in 5,6,7,9,10, 12-18, 20,22,25,28,30,etc, up to 170mm though not all sizes in all grades.
Most of the obvious gaps are filled by approximate imperial equivalents.
i.e. no 19mm listed, but they carry ¾"
Bill
Edited By peak4 on 15/06/2020 00:09:50