I am glad that Mick Butler mentioned the Villiers though it is stretching the meaning of words to call it a derailleur. I am just fitting one to a bike out of curiosity. Given that Morgans started life making transmissions with two chains and a dog cltutch and Frazer Nash made a heavier version of the same idea, it would be nice to think of a Villiers equipped bike as a pedal powered 'Nash. Unfortunately, weighing it in my hand suggests otherwise. Very heavy! I am not too sure about claiming Witmy as British. It should really be pronounced as 'Vite mis' shouldn't it? You could still buy it (or a similar two speed Cyclo) in the fifties in Britain. Had the French long before given up the Witmy? Which puts up another hare to follow.... did the Witmy remain popular here because it was used in hybrid gearing? On the subject of tube sets and nationality, who made Tubor? And don't forget that on pre-war bikes you are as likely to find Accles and Pollock or Chater Lea.
Stuart Tallack on the Sussex coast.