Re: Best solution ...
"Are you being deliberately obtuse? You wouldn't set UI at the level required by severely disabled people - you would create a safety net level for everyone and then those with exceptional circumstances would get extra benefits."
Are you being deliberately illiterate? I said at £160/wk, i.e., standard pension, it's still unaffordable, and at that rate you still cannot live off it if you want to be housed. So, we cannot afford it at that level, and it wouldn't prevent homelessness. And we get all of the admin involved with extra benefits anyway, so, and I want to make it absolutely clear here, so I will use capital letters, THIS SAVES NO MONEY.
Touting UBI as saving money on admin when all the groups that currently get benefits would need a top up anyway means that there's no admin saved, just a massive amount of money moving from people's pockets to government and then back again. It's utterly mindless, unless you are going to tax capital instead of labour. But you can do that anyway, and just pass it on as increased benefits and a (very small) universal handout, without changing our current system.
The reason it's never been tried on a large scale before is that a subsistence-level UBI is stupid. Everybody who can add up knows it's stupid, and if you don't think it's stupid, either you haven't sat down and worked out how it would work, or you cannot add up, or, I'm afraid, you are stupid.