Lt.Col Gardiner was married in 1938 to Doris Elizabeth Sutton (1916 - died by 1994); their daughter, Antoinette Avril Gardiner, became Princess Muna al-Hussein in 1961 as the second wife of King Hussein of Jordan.
He was last known to be living in Jordan in 1999.
References
to have illegitimate descent from Maltese nobility; the father of her maternal grandmother, (Gertrude) Ruth Green, being unknown.
However, that website provides no evidence to support its claims within the site, or subsequently on genealogical forums.