I don’t think so.
the Ted Williams bikes I have seen from Europe had ‘531’ now it may have only been that One Tube- I doubt Reynolds geared up the mandrels and dies to make that.
schwinn did get Huret to make up front derailleur for the Varsity and Continental but those were big volumes.
Campagnolo had a known issue if closing up on French metric 28.0 tubing.
why do you think so many upper tier French frames had a brazed on stop for the down tube shifters?