This is a great video. It tells you all you need to know. Layed hedges, especially those with a ditch and bank and using a lot of thorn species is a very solid barrier indeed. When I get on some land (hopefully REALLY soon) I'm planning on planting for this kind of hedge.
Apparently I'll need to plant on 20cm (9 inch) centers and wait until they are 2.5m (8ft) high before the first laying.
Netherlands Zone 7b 930mm (36 inches) rain, 1500 sunshine hours
please buy this thing and then I get a fat cut of the action: