It was first sung "in something like its present form" in 1745 at the Theatre Royal, Drury Lane where it was performed after the first production of the Ben Jonson play The Alchemist, and was arranged by Thomas Arne, who composed the music for "Rule, Britannia!" The melody appears to date from the time of William of Orange, and the opening words were:
God bless our noble King God save great George our King
These had already been published in Thesaurus Musicus the previous year; the publisher brought out a new edition with revised words and a third stanza, and it was republished widely.
The music for "God Save The King" also became the first American National Anthem in 1831 as "My Country, 'Tis Of Thee" with new verses composed by the Reverend Samuel Francis Smith.
When Queen Victoria ascended to the throne in 1837, the anthem was of course altered to "God Save The Queen."
Suggestion credit: Alexander Baron - London, England