Moving a young tree.

[BCSurvivor]

I have a well established 3 and a half year old elderflower tree currently positioned in the wrong part of the garden.
Long story, but basically it is in a shared part of the garden which my toxic neighbour recently vandalised - twice - so I now feel it would be better to move the tree to my own private garden.
My neighbour doesn't seem to like plants.
I love this tree, but although elderflower trees are quite compact it does already have a 4 inch wide trunk.
The new location would be perfect as it gets full sun, but never having transplanted a tree older than a year or so before I am unsure whether it would survive.
I wouldn't transplant it now, and would wait until mid autumn, when the leaves drop.
Has anyone successfully transplanted a tree of 4 years old?

Elderflower comes from cuttings really easily, why not get some cuttings going now as insurance? I suspect your elderflower won't be very happy about moving.

@olderbutwiser thank you!
I'll go and consult Google, as I've never taken a tree cutting before, and I love this one.
Is it quite straightforward to do?
Can it be done in the growing season, or should I wait?

You can start to prepare it for moving now. You basically go round the tree with a spade taking out a trench all the way round. Make to rootball as large as you can feasibly lift ( with a few friends to help!) Fill the trench with some nice compost and keep well watered. The severed roots will grow back into the compost but you will have a more compact rootball full of fibrous roots.
When the leaves have fallen in the Autumn, dig a new hole in your preferred spot. Dig up the tree, going as deep as you can and slide the tree onto a tarpaulin, keeping the root ball together as much as you can. Carry or slide the tree over to its new spot and place in the hole. Check it’s at the same planting depth as before. You can slide the tarpaulin out from underneath. Back fill, firm, water and mulch. Apologise to tree! It might need staking.

@AlwaysGardening thank you so much, that is so helpful!