The Mail on Sunday has taken the trouble of locating the church book in which the then Prince Philip of Greece's birth and christening was recorded. [External link]
Prince Philip was born at the royal estate of Mon Repos on 10 June 1921 (28 May in the old Julian calendar) and baptized in the Church of Our Christ the Saviour,
The record is dated 24 October 1921 (i.e. 14 November 1921, Gregorian calendar).