Thank you so much all for responding, especially Jaspersmom for the great links and advice (I always forget to do searches on here for the topic so please excuse me!). I've had a good read through and I think he's going to be just fine. His dad was a show dog and had the ideal colouring standard and his mum was much darker round the head but beautifully proportioned and built - even better than the dad really. The breeder said she was darker because she was still fairly young and one of the reasons she had bred from her was for colouring purposes to maintain the darker points. In any event, I will keep an eye on it all (at the end of the day it doesn't really matter) and keep you all posted with how he gets on. If all else fails, I'll whip him down the hairdressers for some highlights!
p.s. Olivier is a darling!