Brazeons are quite nice. Campag dropouts...
If weight of bike is around 10kg, rear axle width 120mm and seatpost is 27.2 then chances are you have a mid-late 70s 531 or Columbus butted frameset, going by the fork crown and band-on brake cable guides and shifters.
You can find out country of origin by looking at BB threads.
If a lightweight 70s race frane is what you've got, you should make a fixie out of it... (Yes i know I am repeating myself) - with no rear brake of course. You wouldn't even need to fit track ends and the geometry and aesthetics are spot on...