the royal baby could be called sam , after duchess of cambridge 's friend .
sam waley-cohen , who rode in the grand national , is a close confidant of the duchess and helped the cambridges rekindle their romance in 2007 .
odds on the royal baby being named sam have been slashed from 66/1 to 20/1 since waley-cohen appeared at aintree and won race on friday .
royal couple have insisted they do not know the sex of their second child .