It has to be said that the Duchess of Cambridge is rather fond of a touch of blue, it seems to be a colour she wears again and again. Last week she attended an event at The National Portrait gallery wearing a vibrant Stella McCartney cobalt blue shift dress that to me was very reminiscent of the sort of styles worn in the 1960s by Jackie Kennedy. The blue was very vibrant and made a great backdrop for the special Olympic rings necklace she was also wearing that day. It is said Kate wanted to wear Stella to tie in with the designer being the official Olympic kit designer, and…