That's tough to answer, since there weren't -- and never have been -- any rainforests in England in the first place. Therefore, they can't disappear. Unless, of course, you mean the lush prehistoric flora of the Mesozoic Era -- which still doesn't technically count as rainforest, but that's the closest England ever got to rainforest. Those disappeared with the same climate change which wiped out the dinosaurs. However, that would really have to be "disappeared" as opposed to "disappearing," as the process finished at least several hundred thousand years ago.