If anybody's still interested, two-and-a-half years after the question was posed in this thread, The Vicar and the Frog was written by Stan Crowther. He has a reputation as a fine songwriter, tarnished only by the fact that he later became Labour MP for Rotherham

THE VICAR AND THE FROG

There once was a very, very holy vicar
And he was a-walking down the street
When he heard a little voice say: "Excuse me, vicar,
Help me, vicar," the voice did say.
Well, the vicar looked round, but all he could see
Was a tiny frog sitting on the ground.
"Was it you little froggy, was it you who spoke?
Was it you who spoke when I heard that sound?"

"Oh, yes," said the frog, "Oh, help me, vicar,
For I'm not really a frog, you see.
I'm a choirboy really, but a wicked fairy
Cast a nasty spell on me.
And the only way that I can be saved
From that evil witch," the little frog said,
"Is for someone to take me and put me in a place
Where a holy man has laid his head."

Well the vicar took him home and he put him on his pillow
And there he lay till the break of day.
And lo and behold, now, a blessed miracle -
The boy was saved I'm glad to say.
For there lay a choirboy in bed with the vicar,
And I hope you think this all makes sense.
For there, My Lord, and members of the jury
Rests the case for the defence.