English Hedgerow Trust
Hedge Link UK
Cornish hedges - www.cornishhedges.co.uk
Devon's hedges - www.devon.gov.uk/index/environmentplanni.....
Isle of Wight hedges - www.iwhg.org
Somerset hedges - www.somerset-hedgegroup.org.uk
Irish hedges (Hedgelaying Association of Ireland) - www.hedgelaying.ie
National Hedgelaying Society
Site includes information about styles of hedgelaying (Midland, etc.)
See also Conservation Techniques.