down-portting an apple tree

This King of the Pippins on an M27 dwarfing rootstock is one of my first patio fruit trees. It’s been a good and faithful fruiter over a decade or more in a large tub, so it doesn’t dry out. I have a couple of other King of the Pippins but my patio garden in West London needs thinning out so I’m down-potting this dwarfed tree to take it to Keswick; the root-ball is anyhow quite small. My two apple trees in Keswick are growing fine but slowly and I’m not expecting significant crop for a couple of years more yet.
Note the Mandarin fruits on the tree on the left.