My memory of it is as follows:

Johnny Todd he stole a Z car, just to give his bird a ride,
By another was overtaken, Johnny Todd was soon inside.

18 months was Johnny's sentence, how she wept when he went down,
She was escorted from the courtroom by the handsome Sergeant Brown.

Do not weep my pretty maiden, I am strong and six feet tall
And you shall dance with me tomorrow, when we hold the policeman's ball.

You shall have both gin and orange, music sweet and softest light,
I'll give you my policeman's truncheon, 'twill take care of you all night.

Johnny Todd came home from Walton, to seek the love of his young life,
But once more he'd been overtaken, for she was the Sergeant's wife.

So all young men who go a-courting, shun the paths that lead inside,
Or you'll be left on your tod like Johnny, it's you that's taken for a ride.

(Sorry, but I have no idea of its provenance).