Two trees actually and they are both walnut trees too. The farmer has marked them both with plastic electric fence post and he's softening the ground so that he can lift them complete with their root ball and transplant them at the end of his orchard.
They'll both have to be lifted before the combine harvester comes to cut the wheat, if he doesn't get them lifted by then there will be some radical and terminal pruning taking place.
Usually these walnut seedlings grow from nuts that have been dropped by the crows hoping to break them open for the nut feed inside so these must be the two that got away, most probably they sank into the soft ground and the crows couldn't find them.
There you are, two new trees on the West Norfolk skyline, well there will be eventually.