in the UK it is inhumane to put a dog in a Police cell, is that why homeless guys always have dogs?

Eh? What on Earth are you on about man?! Anyways, to answer your question, if someone is arrested in possession of a dog we put the dog in one of our kennels. Pretty much every police station in London has kennels. Not sure how it works in the provinces.

So they don't go in 'police cells'. Just cages...

lt was found that homeless people did better with a dog. Having a dog gave them something to look after, something to help with the loneliness, something to love and something which returned that love and for which they had responsibility. A dog would be quite happy in a police cell as long as he was with his master. [yes of course, in reality the dog would be put in the kennels]

It wouldn't be inhumane, but they are usually put in kennels outside. I am sure that this is not the reason why homeless people have dogs. It's for company.

since when were dogs classed as humane, in or otherwise,

but I get your point about homeless people.