I'd wait until autumn to move, dig a good size planting hole and, if possible, put some well rotten compost or other organic matter in then lift the Hawthorn and plant in the hole - back fill and keep watered to allow the roots to establish. If you are using to fill in gaps in an existing hedge you could cut the top grown back but a third to help the tree establish new roots. Truth is Hawthorn's are as tough as old boots!

I would try to find out why those patches are thin, first. Why throw good hawthorns after bad, even if they are free?

Thank you Moon growe, that's helpful.

Good point Tugbrethil, thanks for the comment. The hawthorns were cutback too hard some years ago by a previous owner for a shed to be erected which has now been dismantled.

Gilbertb