I think it’s called coppicing, caused when the young tree is damaged or deliberately cut for varying reasons. It then grows multiple trunks, I’m sure someone with more knowledge will be along.
Because it is so big, I wonder if it is a beech coppice? (see pic) I cannot see the leaves that well.
We have a few hazel trees (corylus). They have a similar leaf to beech but don't grow as high. They naturally seem to grow as a coppice, and we just hack some shoots down to the ground every few years to keep it in check.
With beech I think unless it was damaged early on, it normally grows on one trunk, so these have probably been coppiced.
I shall take some photos of the leaves tomorrow and hopefully the mystery will be solved!
I think there are about 5 or 6 along a small path that leads to the woods. It's very sandy soil. There's quite an array of trees and shrubs down there. We also get lots of bluebells and daffodils down there. Not sure how they got there!
They are probably hazel trees. They grow multi stemmed naturally, so your trees may not have been coppiced. Did you notice any catkins in the early spring? Have a look for any developing nuts. Try google lens with your phone, if it has that capability, it is quite a good tool for identifying plants.