Viking was a very thriving company in the 50s, based in Wolverhampton, I think. The company made all manner of family bikes, but promoted the brand via a Pro racing team. The team's finest victory was Ian Steel's winning ride in the Tour Of Britain in 1951 (or was it 52?). He also rode well on the continent around that time. The top-of-the-range bike was the Severn Valley road racing machine that had, as I recall, Nervex Pro lugs and a copper-plate finish with some chrome highlights (lugs etc). Inevitably there was an "ian Steel" replica model.
As for track frames and a "made-to-measure" special order department, I can't remember that aspect although I do have a track frame with Nervex Serie Legere lugs and looks as though it might be from the 50s. It's a very functional frame, with few signs of the refinement and attention to detail that might be expected from a "special".
There was of course the uniquely designed SBU model with its extended down tube and twin chain-stay configuration; rumour has it that as few as six of these were produced. Perhaps the company did have a bespoke frame workshop.
Norris Lockley ...Settle Uk