"He is trying to make political gain out of human tragedy. Sick arsehole."

Gnome that is precisely what Corbyn and his supporters have been doing from day one.

On the empty property thing - One of the examples of the blocks of property vacant given belongs to the Algerian Embassy and therefore cannot be touched by the British Government. Don't know who "owns" the others. Like most things in life, especially in large, complex and multi-national cities and there are few bigger than London what appears to be a simple solution to an immediate problem is far from being simple or indeed being any form of solution at all.