Sean, those window frames are valuable enough if you are taking other stuff to weigh-in. They are aluminium, and probably quite heavy.
Believe it or not the lintel bricks have probably been removed so that they can rip out the lead soaker sheet. It's a bit desperate for the few pounds they would get for it! Complete structural collapse, certainly of the outer brickwork, will surely follow.
Sad times, but unfortunately not all that surprising.