Blackthorn produces sloes which are edible after soaking in Vodka or Gin for 12 months (so they tell me, being allergic to alcohol I have never tried it).
Interweave any other hedge plants with Blackberry canes, that would produce fruit for use.
Rose hips are edible, so Rosa rugosa might be good.

Thanks Owdboggy - I'm a bit green & not an experienced gardener I didn't know blackberries grew as "canes" so that is a possibility, perhaps I could grow them amongst the pyrathanca

If you want some interest and prune if it gets excessive then Elder is good. Elderflower cordial or elderberry sauce, rather like a dark cranberry sauce......or elderberry wine of course

Don't forget Pyracantha berries are not edible.

edible by whom? you or i or the birds. if it is birds don't forget a shrub rose like rosere de la hay. hips for the birds and and dead thorny for the unwelcome visitor. the other possibility is a holly. get a really vicious thorny one

get a shotgun and put some buck-shot up his ass

I wouldn't plant blackthorn if I were you - it suckers all over the place sometimes a long way from the parent and is quite hard to keep under control once its mature.(She said ruefully from experience!) However it certainly is thorny - bear in mind that it wants to be a small tree so you will have lots of very prickly prunings to dispose of as well.
Why not have fence of chain link or strong chicken wire and grow your hedge close so it covers it. Blackberry makes very long briars, can be about 12 feet long, and its best to cut out all the canes that fruited in the past year and train in the new growth, so although blackberries are wonderful they come at the price of some labour and as they need support they'll need to be grown through something else..Pyracantha would make a good support but I think it would spoil the look of the pyracantha, but that's just me.

Gooseberries make a prickly hedge and if you prune them carefully they will grow to about five feet in time. But realistically can't think of anything that will give you good edible returns when grown as a hedge. Also remember if you grow fruit trees on your boundary children will gather round...

Why not stick with pyracantha and grow your fruit bushes inside it?

Well, you can't eat pyracantha or holly or berberis although they are probably the best 3 for deterring intruders apart from the blackthorn with the problems already stated above. If you want to feed the birds then these 3 are ideal and I like the idea of growing gooseberries and raspberries inside, assuming you have room for a double hedge.Another effective barrier can be made using really thorny but very pretty roses such as rugosa.

I would just like to thank everybody for all their suggestions, I am thinking Pyracantha under the windows. And a mixed perimeter hedge of various prickly thorny shrubs, some of which will bear fruit & berries to eat through the year. Once again thank you, I'm delighted with the response.

PS Pennyfarthin - I have found recipes online for pyracantha wine & jelly/jam :) which would be fun to have a go at making...

Ornamental or japanese quince is very thorny and produces small fruit which can be peeled and added to apple pies for a mellow richness. They also have beautiful blossom and attract pollinators.

Thats a good idea.

Pyracantha wine?? wow, but you'll have to be quick to beat the birds. the blackbirds to so enjoy them when the weather gets cold.