Though little used, nine bark does seem to have some potential.
I don't know your climate, (thought Yorkshire was in England)but you can usually dig up and "bonsai" a landscape plant just as buds are swelled and ready to open in the early Spring. Did you just recently prune that back? Would have been better to do it at the same time that you dug it up. Now you don't have buds to help time the dig.
You have multiple trunks that you may be able to separate and create 3-4 trees from this plant. Definitely doable. Show us the results!
CW