WhtANightmare
Devout Dirtbag
Potentially this is just a version of the coronation frame that has over the years had a few changes to it. Looking at some of the photos of the grandad it looks like when he raced he obviously didn't use mudguards, so maybe he adapted the bike to run 27 x 1 1/4 for this purpose although still doesn't really make sense that the front and back calipers are seemingly for two different rim sizes