This song from the award winning musical My Fair Lady had a rather unusual inspiration.
According to Dominic McHugh of the University of Sheffield in the one-off documentary Michael Grade's Stars Of The Musical Theatre, leading man Rex Harrison was not entirely happy with his role. One day, he and lyricist Alan Lerner were walking down 5th Avenue talking about their marital problems. Harrison's first marriage ended in divorce in 1942; his second wife lasted from 1943 until 1957, and he would eventually marry no fewer than six times. At that time, Lerner was on wife number 3 (or possibly 4); he would go on to marry eight times! There must be a song there, but somehow "Alan The Eighth" doesn't have quite the same ring to it as the name of a certain infamous king.
This prompted Harrison to shout out to Lerner: "Wouldn't it be wonderful if we were both homosexuals?" which even in the 21st Century is not an appropriate title for a song. However, Lerner was inspired by some lateral thinking, and produced the lyric for this one.
Harrison was the third choice to play Henry Higgins in this show, the second was Noël Coward, and if he had been chosen to play the lead, this song would never have been written!
Suggestion credit: Alexander Baron - London, England