Following the recent forum post and given the increasing demand from both private and commerical clients, (the latter as a result of the UK's ratification of the EC Landscape Convention). It is worth gathering information on the history and proper methodology of building these structures, which is relatively scant to the say the least. Certainly it is evident that both in Devon and Cornwall many of the walls which have been built recently, particularly the large scale, roadside and new housing estate structures, fail to meet the traditional and sustainable elements which make these structures so unique internationally. this is not the fault of the landscapers building the walls but a mammoth failure to understand the true heritage of these structures.
The structures are known to date back to neolithic periods. The reason was simple, using the stone, (or in many parts of Devon, where due to the geography and geology loose stones were rare and turf was used instead), which were spread across the landscape to create a boundary to enclose livestock. The walls over the years became more solid, additional smaller stone and waste material was added to create a core thus enabling higher walls. This meant that larger livestock could be farmed together with providing shelter or windbreaks for crops by minimilising the need for larger trees to be planted. And these walls were completely unique to particular areas, (up to only 30 years ago it was possible to drive around and discover not only the direct geology of an area, but also a good guess of the depth of top soil by simply looking at the hedges), differing dramatically in style in less than a kilometre. An example of this can be found easily on the North Coast of Cornwall, much smaller stones closer to the sea are freely available as such herringbone and vertical patterns were easily achieved. The very loose backfill material allowed for steeper sides also. Yet only 5 miles inland the rock changes to a different slate formation, much larger stones are then used and as such it is simpler to built the wall in the horizontal pattern. One area well worth seeing is the Mylor Bridge area, here many of the walls are constructed from the underlying quartz, which creates walls which when seen close up can sometimes reflect rainbow colours. The trees and growth on the walls was also distinctly different - as with native tree mixes in our ancient woodlands the mix of species on the walls changed dramatically.
Stiles had always been incorporated, but bee boles, milk urn shelves and underpasses started to be introduced more and more. Wildlife populations in these structures was high and the hedgerows started to act as motorways for wildlife. The list of species found in these hedges is almost as long as a list of UK fauna & flora.
There is considerable evidence that until recent history these walls were mainly built by women, and following the enclosure act, the landowners started to demand much more elaborate walls, which would illustrate their influence. As such many new walls were built in square cut granite and other intensive or imported materials - the death of the sustainable hedgerow started.
Now as you drive down the A30 there are miles and miles of uniformed 'Cornish hedge', built to a relatively new standard introduced, (even the tree mixes now recommended varies little throughout SW England). This is more attractive than fencing, one has to admit - but it takes no account of the differing areas of Devon and Cornwall, the varying heritage and most importantly is built using imported top soil, which is simply an extreme overkill and not good for the longevity of the hedge. Paradoxically the material removed for the necessary ditch operations is used elsewhere. As such the Cornish and Devonian Hedgerows are no longer the beautiful and unique feature they once were and its only the small scale stonewallers and the more insightful clients who are maintaining or constructing new walls in the traditional manner - stone from the local quarry or even from onsite - hedging mixes matching the ancient hedgrow species and styles incorporating from the outset habitats for beneficial wildlife species, but this is minimal against the destruction of these structures which has occured throughout the 20th century.