Capt Graham-Watson was appointed Equerry to HRH The Duke of Cambridge, Colonel of the Irish Guards, in 2014. He is the second son of Andrew FitzJames Graham-Watson (born 1957), by his wife the former Brigitte Jeanson.
Capt Graham-Watson and the Duke of Cambridge are both of Boothby descent.
Capt Graham-Watson announced his engagement in 2014 to Dr Celia Campbell, a daughter of Robert Campbell, of Rockport, Maine, USA. I do not know whether this marriage ever took place, or know of a subsequent engagement or marriage to the abovementioned Serena.