Several young fruit trees (plum or pear or gages?) (Wolverton MK12)

I often get self-seeded fruit trees on my allotment at Wolverton. They spring up near plum and gage and pear trees so I cannot say exactly which they are but anyone is welcome to come and dig them up (I have a fork and a spade you can use). I have included a photo of one of the grown trees which self-seeded about 3 or 4 years ago I think. They look so vigorous that I don't like to dig them up and waste them - please give them a chance somewhere else! Collection by appointment, best after wet weather to make it easier.