About 25 years ago I found a hawthorn tree growing from a seed, dropped by a bird I guess. I transplanted it into a border, and now the trunk is about 7 inches (17 cm) diameter, but it's not very tall. With pruning and training (I'm not sure how), it's become a low pollard at about 3 feet, with dense growth to 6 feet. In the photo, the trunk is about one third from the right, branches extend to the upper left along the trellis.
This thorny tree growth is popular with birds, especially with peanut/seed feeders nearby. It gives them some protection from cats and other predators. I just trim the "hedge" section once a year, wearing heavy duty leather gloves of course. Hawthorn is relatively slow growing at this altitude (850 feet), and can be shaped by severe pruning if necessary. It usually produces flowers and berries on the previous years growth. Another bonus, it doesn't spread by producing "suckers" or from bits of stem lying on the ground, unlike blackthorn and some willows etc..