Dear Max: A fairly large company got control of an old Army artillery range in southern Massachusetts, and hoped to put in either a very large housing development or an airport. The trees there were only perhaps a hundred years old, but even with chainsaws, chippers, and all sorts of gasoline powered tools and burning, they gave up and just left huge trunks lying on the ground. I doubt very much that the technologically disadvantaged early Britons could have accomplished anything by burning. The could kill trees, but it would have taken hundreds of years before the trunks would fall.