I have what I think is an interesting question concerning Reynolds 531 tubing. The background to the question is that in 1938 two UK companies Tube Investments and Stewarts and Lloyds undertook a joint venture to build and operated a steel tube mill in Kilburn South Australia. The mill was known as the British Tube Mills (Australia) and became a large supplier to the Australian bicycle industry, particularly in the war years and post war period when tube could not be easily imported from Britain. Tube Investments was at the time the owner of the Reynolds brand names. An interesting ad for BTM product from 1952 shows the transfers used on bicycle frames made of their tube.
http://www4.tpgi.com.au/
Two of the transfers make reference to Reynolds and one of them refers to Aircraft Tubing Reynolds 531.
This raises the question as to whether "Reynolds" tubing was produced anywhere else in the world?