The craze for this type of hybrid machine started in the mid 50's and lasted to about the early 70's. These dates are a general approximation. Road/Path models were used for everything from general club riding, time trialing, grass track and pure track. On the track they were used in sprints, pursuits, point to points and devils.Our outdoor tracks of this period tended to have quite shallow bankings. Basically they were 73 degrees parallel with a bottom bracket height of less than eleven inches and a wheelbase of around 41" invariably with mudguard clearance and brake drillings. The type of track ends used on these frames were the special 2" long slot type. This allowed wide variations in gear ratios especially when using inch pitch. Our pure track bikes of this period were of a much shorter wheelbase less than 41" and with a bottom bracket height of over eleven inches. No mudguard clearance or drillings and free from any braze-ons. Typical head angle of 75 degrees and seat of 73. Just to confuse you even more on these type of models there was a fashion in the 60's to have a road/track built with Mafac cantilever bosses brazed on the front forks. Primarily used for time trialing the weight of these machines with all alloy parts was around the 16 pound mark on fixed wheel. These were also used on the track if you could get past the scrutinizers, sometimes they refused or just asked you to tape up the cantilever bosses if you were lucky. These frames were often fitted up with a trike conversion and used as winter hacks. If you care to dig out your old 60's Cycling's there is a road test on a Mercian built to this type of specification. I have a 1960's 24" Allin Stan Butler just like this for sale. Please contact off list.
Best wishes and be lucky. Michael Butler Huntingdon UK.