If you want to thicken your hedge then if you can get a load of Lonicera
nitida cuttings (about 9 to 12 inches long) early October then remove the
top inch or so from them, strip the leaves off the bottom 6 inches then
stick them into the bottom of the hedge about 6inches deep and 6 inches
apart, you can always do this on both sides of the hedge.
Not all will take but you should have enough that root to help fill your
hedge quite quickly.
I did this with a hawthorn hedge 4 years ago and about 70% rooted and grew,
I now have a good thick, hedge with enough of a barrier to stop anything
coming through (Except cats, foxes and badgers).

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk