Hello All I've checked back though my catalogs and the Airweight appears in the 1952 Brown bros catalog but not the 1939,so it looks like they're post war. also available in 52 were the Continental and the Tour de France both in alloy. I cant find a definite finish to production but my guess is sometimes in the 1960s . Also at some point there was a change when the riveted on metal model badge , went to a thin foil stick on .
Cheers Pete Paine Watford