Dear Martin, Now this is going to throw a spanner in the works. Claud Butler, Hobbs of Barbican, Jack Taylor, Holdsworth, Gillott, Ephgrave and countless others have all called their lugless frame in their various makers catalogues of the period " As or of Welded Construction", which I think is the same as fillet brazed. But where do Royal Enfield and Dayton fit into the CR scheme of things (definition). Both makers made lugless frames in the 40's and 50's and had a lot of racing successes. The Dayton welded process was called "Amalgam" and Royal Enfied "Unitized". They mitred the tubes as normal practice and then they are held together in a frame jig. An electric current is passed through which melts the tubes at the joint, due to the high local resistance there. As the tubes melt, welding pressure is applied. The manufacturing process is very quick and the joint requires no subsequent cleaning. The finished frame is consequently cheaper than those produced by other process ( Dayton Park Royal Press release). Dayton had a 6 Day trade team on this type of Amalgam frame and there are several well known press publicity photograph's of Joe Louis "The Brown Bomber" with the Dayton team. Royal Enfield had loads of wins with their version. I think it was an American developed process called "Flash Pressure-Weld they devised it but it was the Brits who really used it to produce high quality volume made lightweights. They must surely fit into the CR scheme of things. Take care Mick.
Thats all for now. Keep those wheels spinning, in your memories if not still on the road. Be lucky Mick Butler Huntingdon UK.