Thanks for replying Moss. In answer to your points:

1. The Tree Register (TROBI) doesn't have jurisdiction over the trees. However TROBI is a recognised organisation and does have _link_s with landowners, the Forestry Commission etc. on a professional and personal level (some of its patrons and members are themselves landowners) and so approaching these parties would best be done via TROBI.

2. To my knowledge there are no dedicated canopy researchers as such in Britain but I'm sure there must be some ecologists who have studied the canopy and may have even climbed into trees as a result. Thanks for the suggestion - I'll look into it.

3. The current height measurements were done with a sextant and more recently with laser clinometers. These methods have been found to be quite inaccurate with trees often needing remeasuring using the same method, coming up with results which differ, sometimes by a couple of metres!

As far as I know, only one company called Tree Dimension in north Wales has ever measured any of these trees by climbing it - the Lake Vyrnwy Douglas Fir, which is situated near them. They (as I'm sure any arborists in Britain are) didn't seem to be equipped for this kind of job - using a 60ft ladder to reach the first branches (scary!) I don't know how they climbed to the top from there but they dropped a length of rope from the top to measure the height (hardly accurate due to rope stretch). The result (62.5m) put this tree ahead of the 62m measured by laser for Dughall Mor in Scotland. A debate raged for 3 years over which country had the tallest tree until the Forestry Commission measured Dughall Mor by laser again, recording a height of 64m.

I'll take a look at the ENTS _link_ now. Again, thanks for your help.

Michael