In reply to Axel Smeets:
http://www.arboristtreecare.co.uk/
These people did a very good job at my Dad's house, the crown was wanting to be thinned by a third, and they did it really sensitively or 'naturally'.
He said he wondered whether they'd got round to coming to do it yet, before looking up to notice how the light was coming through the crown more and that some branches had vanished, and spotting a few small twigs on the drive.