Get hold of a load of pieces of Lonicera Natidia about 12 to 15 inches long
in Sept /Oct and stick them in about 6 to 9 inches deep all along the
hedge,every 6 inches or so.
Many will root over the winter, and will grow through the thorn.
I did this 3 years ago and the 300ft hawthorn hedge has filled well.
They wont all root but enough will to do the job.
You should be able to scrounge the pieces if you are lucky.
--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk