If you go on allbreedpedigree.com and put in the name of your boy's sire, then click on 'Reports' then 'Progeny', it lists 19 ponies. Obviously this isn't an exhaustive list, as allbreedpedigree relies on people putting their own pony's details in....
http://www.nfstallions.info/ . . .
http://www.forestuprising.org.uk/