Heh, I met a chap doing a PhD in maths at a decent university in Northern England (no names), he was in his 8th year: He was funded for the first 3 years, managed to get another year of funding when that ended and subsequently lived off his parents. By year 6 they were a bit sick of this and stopped, so he had no money for rent so started to live in the department, working until late in the evening and then sleeping in a cupboard. He'd been doing that for 2 years when I met him. Perhaps he's still there ...