The tree was over 70ft and would have required muscle and specialist equipment to chop down cleanly.
Someone holding a torch would have been needed to know where to cut. That suggests an accomplice.
The Sycamore also appears to have been cleanly sliced at the trunk - leaving behind a smooth stump.
Mike Pratt, chief executive of the Northumberland Wildlife Trust, believes a professional was behind the vandalism.
https://www.thesun.co.uk/news/24197547/three-clues-sycamore-gap-tree-cut-down-planned/