Have a pony who does mounted games (done Prince Philip Cup mounted games), show jumping (won both classes entered in the weekend before last) and is great all rounder in Devon where is the best place to advertise him for free?
Well, it depends how much publicity you want of your horse.
The popular American advertisement websites (such as craigslist) aren't as popular in the UK.
A very popular website to sell horses on is:
www.horsemart.co.uk
It's the 2nd link to appear if you put in "horses for sale" in Google, although it costs £15. If you put a horse up for sale on a site like this (or like horsetrader, horse and hound) you're going to look more reputable than a free site.
On the other hand, this site:
www.stabletalk.co.uk
Is a very popular site for those in the UK looking to advertise for free, and you can advertise anything equine related. It has thousands of hits a month and the ads are regularly updated.
Hope i helped.
I think you will be better off spending a little bit of money advertising in a magazine like Horse and Hound, otherwise you're just going to get inundated with riff raff - wouldn't you rather be confident in the knowledge you have sold your pony to someone with a keen interest and at least some knowledge of the animals?