Nigel:
I think the Biarritz became more formal and symmetrical as Macdonald gradually handed over the work to Raynor. Raynor never visited France (or Scotland!), and the National Golf Links (where Macdonald explained most of his concepts) doesn't have a Biarritz hole, so he had less idea what C.B. was looking for on that hole in particular. And, to be honest, I'm not sure Macdonald even knew exactly what he wanted. At most, he saw the original hole in Biarritz that gave him the idea once or twice.
P.S. Some of Macdonald's 1926 book is reprints of articles he'd written earlier ... including his description of the template holes.