I think Reynolds 531 as seamless tubing was considered boss hog by both builders and punters. What little info there is around seems to suggest Camus tubing was readily available (in France) and easy to work with. It's natural competition was maybe Vitus. Peugeot and the like could probably...
https://www.ebay.co.uk/itm/176302922842?itmmeta=01HWD367Z1HVMPQX197SA5MR4N&hash=item290c791c5a:g:2WwAAOSwYzxmAJgB
Ok, not as offensive as the the glitter encrusted BSO - but also not as funny. Somebody took inspiration from the 1973 British Leyland catalogue here. This is apparently...
https://www.ebay.co.uk/itm/296146211108?itmmeta=01HWCWHFSH0SENE33XHP47SWGE&hash=item44f3b09124:g:wQgAAOSw0-xllt87
Camus 779 tubing, double seat bolt action from a now gone small volume builder in Picardy. Unsure if les filetages sont Français ou Anglais? Probably Français.