On reading that, my first thought was why are people earning more than £100k a year in council houses anyway?

it is already an offence, it's a breach of tenancy, think it may be civil as opposed to criminal though.

and you can, in theory, mutually exchange between council areas, the problem is that the allocations policy vary widely between areas.

because you are only assessed once, and once you're in, you can stay regardless (ask Bob Crow)

But it is a bloody nightmare to do, there is no reason why outside of the major metropolitan areas we can't come up with an exchange system that works.

I can give you a bl00dy big reason, politics.

It's been tried before, I worked on it in Glasgow to set up a city wide scheme to be able to transfer between different providers and it all worked fine until various comittees involved and then it collapsed.