Hi Doug

I think those are not Nervex but rather "continental" French Prugnat (62S?) lugs. Prugnat first introduced by Holdsworthy in 1963. The rear dropouts don't look like Agrati as on Cordon Bleu. Simpler pressed steel. Looks to me like Challenge frame. I believe this is same frame as Classique and European but built up differently. Likely a '63. Have a look at kilgariff catalog. Just click catalog then click model.

Doug