This one has me scratching my head. It is Claire Austin, which can be seen here ...
http://www.helpmefind.com/gardening/l.php?l=2.44031
... and indeed it was a white rose when I bought it. I am not sure whether these pink roses are sports it has produced or not, I sort of doubt if just weather could make such a change. I'll tag the branches and see what colour they produce in future.