Many "Mini bloodlines" contain heavy Shetland breeding.
Technically a mini is just under 38" tall.
That said I have a good friend who paid quite a bit of money for a silver bay pinto filly who was triple registered, AMHA/AMHR/WC. She was supposed to mature at 32" tall - needless to say she is in fact 42" tall and built every bit like a fat, stocky, grade looking pony with no miniature horse qualities to speak of.
He could very well be a mini who went over, a mini x pony cross or a Shetland, hard to say :)