The CoB and Lord Mounbatten had a close relationship and even LM acted as a negotiator between the CoB and the British Govt. to try to restore the monarchy in Spain in the 40's. It was Mountabatten who informed Juan that, after Potsdam, the restoration in Spain was not a priority.
I remember a picture of Prince Juan Carlos and Princess Sofia on the stairs at Broadlands with other royals. I think it was a wedding anniversary of Lord and Lady Mountbatten.
: I think Louis Mountbatten visited his cousin
: Ena a few times in the 20s (on his
: honeymoon), and I seem to recall it was his
: influence with the family that led Juan of
: Barcelona to join the Royal Navy.