The Claud Butler is almost certainly an Olympic Sprint as you suggest and the 523 number on the BB indicates 1952 March build. It is a top class frame with the long spearpoint, bilaminated lugs that were some of the best in the business at the time. The frame would have been fillet braised without any lugs then reinforced with the bilaminated lugs for extra stiffness. Wonderful craftmanship.
Is the rear bridge drilled for a brake caliper or is it purely a track bike expecting to have only the one brake? It is more than a bit risky on the road with only one brake caliper. It will have been built to take 27" rims (630) rims as opposed to more modern 700c (622) size. The latter may well fit but the 27" do look better if you can find some. There are plenty of good ones still around at cycle jumbles.
