Can you help to identify these frames, bikes or parts?

I picked up a vintage 531 track bike the other day and now starts the practically impossible task of trying to identifying it.

I bought it from the original owner son, who informed me it use to be his fathers track bike, before it languished in the garage for a fair few year. The father decided to have it restored at Argos cycles in Bristol over 20 years ago and used it for a short time to commute in and out of Gloucester. It's been sat in his shed for a long time around 20 years as his father past away.

It's beautifully made with campagnolo track drop outs (campagnolo stamped on the inside of both rear dropouts), 531 tubing, 27.2 seat posts and beautiful lug work, which I can't seem to identify. It's has a 4 digit frame number on the chain ring side of the bottom of the bottom bracket. It's 110 spacing at the rear and although advertised as being a 700c frame set, it came with a 700c in the front with a 700x20c tubular tire (with masses of clearance) and a 27" rear with a 27x1-1/8 tire with about 2mm clearance either side of the tire in the chain stays. It has a curve seat stay bridge which is undrilled and a curved chainstay bridge too. It's got mudguard eyelets and It's running British threads as far as I can tell too.

Although it's stickered up as an Agros, the original owner's son didn't belive it was an Argos, just restored there, and to be honest I think it is too, surely it's to old to be an Argos, the question is... what might it be?

Anyway this is the bike, although it wasn't 100% as advertised, by the seller, interms or wheel size and general condition. It is perfect for what I want and I kinda like it!!!

I should add, it's currently sporting a 27x1-1/4 rear wheel with 27x1-1/8 rear tyre and a 700c from wheel with 20c tubular tyre... Hence the sizeable gap between the front wheel and the fork crown.