Whilst researching hedgerows for a project I am about to begin work on, I came across this wonderful YouTube clip on Robert Hart and his forest garden (see below).
Basically before the term 'permaculture' was coined there was Robert Hart. After WWII (where he was a military policeman and code breaker) Robert settled down in Shropshire, England where he owned a smallholding and set about the idea of self sufficiency. Following conventional thought he separated his vegetables, orchard and wildstock such as chickens and cows, into separate areas. This all meant a lot of work; and what he came to realise was that some herbs and veg grew better together - and that crops could be grown beneath trees.
What Robert Hart ended up developing was an edible forest system containing seven layers (as found in nature) which worked in harmony with each other and with little work from himself. He was able to grow more food in less space with less work.
An amazing story to watch (there are also two equally interesting clips which follow on the same video).