Winning a Pony
The ultimate dream for many a pony mad child was getting a pony, and some lucky souls achieved it by winning one. Judith M Berrisford's fictional Jackie did it in Jackie Won a Pony by winning a competition in Horseshoes Magazine.
People did it in real life too: Pony Magazine, in its earliest days, ran Win a Pony competitions, which required some dedication. It wasn't a question of whipping a quick essay off or doing a few questions: you had to enter twelve separate competitions over a year. Here's one from September 1950, in which you had to complete the story by filling in the blanks with names from the list of well known horses and ponies supplied.
This is the winner (or at least I assume it is: the competition presumably ran into 1951). Carolyn Brown won Mr Murphy, and this is a photograph of them, reunited, in 1958.

Comments
I guess the organizers hadn't read J P-T's 'The Prize Pony'.
Fiona - do you know when it was? Pony was running competitions again in the 1980s, and I remember W H Smith doing them in the 1970s.
Your Horse mag has also done similiar comps over this time scale (they use to be linked I think) up until very recently.
Aha - in the filing cabinet. In 2007 there was a Barbie competition to win a pony for a year. And ponies as bingo prizes in Sweden. And at the American Shetland Pony Congress.
Clearly I need to move countries to maximise my chances.