it IS very similar to an Allegro stay wrap, but not exactly (at least not exactly like MY Allegro). Allegros usually used a Georg Fisher sandcast BB shell, not a Nervex pro and their serial numbers were on a distinctive brass plate brazed onto the seat tube. But, anything could be possible as a custom frame or limited edition...might be Swiss in any case, might be French...very much doubt it's a Gitane.
Time for some dimensions/figures: OD of the main tubes, seat post size, BB threading?
EDIT: I can read the numbers on the BB: British, so I have to retract my guess about this being FR or Swiss. Probably British...no idea on a specific make but given the Nervex pro lugs,BB shell and level of workmanship, it's high quality.