Unstable plum tree

Llessur starts with ...
I planted the pictured Prune D'Argen approximately 5 years ago but at the time I did not realise that the previous owner of the house had buried a sheet of corrugated steel (presumably as a root barrier to a long-gone plant) around 30cm away from the planting site - see red line on picture.

As such the tree hasn't ever anchored in one direction and can be wobbled quite freely by hand.

I've dug out the buried steel but is this tree ever likely to grow new roots and stabilise itself, or am I better off removing this tree and starting again?

nb. The fence to the rear of the tree doesn't extend underground so there are no problems in that direction.

Pictures - Click to enlarge
Picture: 1