"why love, of course, instant love"

What is it with red-haired women named Mary?

First there's this in Manalive by Chesterton:

This was a slight young woman in dark gray, and in no way notable but for a load of dull red hair . . . Her surname seemed to be Gray, and Miss Hunt called her Mary . . .

Later:

"It's Mary," said the heiress, "my companion Mary Gray: that cracked friend of yours called Smith has proposed to her in the garden, after ten hours' acquaintance, and he wants to go off with her now for a special license."

Then this, which is, as Hollywood says, based on a true story: