Tom,
Concerning Port Marly, it was just down the road from St-Germain and layed out in 1902 by Jean Boussod who rented the land. He was advised by M. de La Lombaredière & Charles Viraut, both golfers who had built 3 holes in the Bois de Boulogne on the edge of Paris.
Frequently flooded by the river Seine, Port Marly was abandoned, & the club (Golf de l'Ermitage) moved to St-Germain (clubhouse included) on completion of the new course designed by Colt. The new president of Ermitage, Georges Durand planned the move & remained president until 1936.
As for Hossegor, it certainly looks more like a Colt & Co than a Simpson, It was definetly John Morrison. Recent changes are rather unfortunate but it remains a very solid golf course with lots of charm. It's probably my favorite in the area, even though Chiberta has a great site & potential for greater things. Biarritz has bags of charm that we rarely see these days, I really do like the atmosphere there.
An excellent varied golfing destination. But I would say that, I live there.