There seems to be some confusion over this piece judging by the replies off list I have received. I was not remarking about the UNIQUENESS OF THE ALUMINUM FRAME but the fact that it had a Aheadset type extension fitting in 1950. Was this a first? Aluminum frames are nothing new they were about a long time prior to the First World War. Many thanks for all your replies and interest.
Best wishes and be lucky. Michael Butler Huntingdon UK.