As far as I know Andrew has never mentioned this. Sir Henry Birkin, better known as Tim Birkin, was a famous racing car driver in the 1920s and early 1930s. One of his daughters married, not once but twice, into the Buxton family and was known socially as "Lady Buxton". So, a cousin of Andrew's married two cousins of Rupert's (please note:at different times). Now, I don't hold with conspiracy theories but ...