The lugs are unusual - originally developed for Carlton while they were an independent company, before Raleigh bought them out. The story is that during a renovation of the Carlton plant, a sizeable quantity were found in boxes, and they were used extensively c.1973 until they were all gone. The general consensus is that they were primarily used in 1973 on bikes that previously had used Nervex Professional lugs - the Super Course, the Competition (now renamed Competition Mk. II) and the International. By 1974 the International returned to Nervex Professionals and the Super Course and Competition to Prugnat 62A lugs. The Capella really needed a lot of handwork to make it nice, and lots of us have stories of crudely brazed and fitted specimens. Stack that on top of the crushing demand for bikes in '73, the peak of the great bike boom, and you get all sorts of hack work. One frequent poster has noted his Raleigh Competition Mk. II has not fully brazed - the tubing and lugs were held together with tacked brazing, and he had everything properly joined when he had it painted. My '73 Competition has some interesting (but fortunately largely cosmetic!) holidays in the brazing of the long lug points.

My experience is that the Competition and the Gran(d) Sport(s), which were alternating models for a few years, have nearly identical geometry, just different lugs, dropouts and chainstays. The greatest virtue of the Competition Mk. II from the sloping crown era is the outrageous tire clearance, pretty much the most of any of the classic Raleigh/Carlton 531 bikes.