Not sure if Mike Horrell is still at it but he was spraying heather with R22's in Scotland until a few years ago. MFH Helicopters I think. He was my FI course instructor and fantastic in the R22.
Yes, Mike is still going strong, Bracken control and Heather re-seeding. MFH Helicopters is who the spraying work goes through.
He is taking me through my PPL(H) based at Peterborough Conington. He also does spraying courses from time to time - I hear those are hard work but amazing to do. Some details on his website
http://www.mikehorrell.com/