I can only think that West Coast is doing a bit of winding up. I can't believe he really doesn't know that Concorde was a British-French initiative.
If he doesn't perhaps there is a general perception in the USA (I assume the West Coast part of his nomenclature is that of the USA) that Concorde is completely French which either says much for the Gallic publicity machine or very little for Britain's.
If he still needs convincing he need do no more than visit Bristol (the original one - in England) where many retired engineers will be pleased to tell him how they built Concorde at Filton which is on the northern outskirts of that city.