We have just left a rented house (I have posted other threads about this) in which we lived for just under for years.
About a year after we moved in, my DH got into conversation with the LL about the row of garages behind the house. The LL said we could use the end one FOC although it was full - and I mean full - of stuff which we would have to clear. Also it wasn't suitable for a car as the door only opened about 3-4 feet off the ground due to being broken.
We paid for hire of a skip, cleared it out, cleaned it up as best we could and used it for storage. Unfortunately, it turned out not to be much good for that either as the roof leaked and a lot of our stuff was spoiled. When we moved, we chucked quite a bit out (hired a skip for the purpose) but due to an unexpected family emergency, we didn't get everything cleared out before the skip was collected.
The man who rents the garage next door to ours asked what was happening to it when he learned we were moving. We obviously didn't know. He said he would speak to our LL as it would do for his little trailer which can be covered with a tarpaulin so incoming rain wouldn't be a problem. He also asked what we were doing with various bits and pieces and we said he was welcome to them.
When we moved out, there was probably about 1/3 of the garage still full. Some of the stuff - shelving units, a few wooden things to use on a woodburner etc - was for the guy next door who hasn't had a chance to move it yet, the rest was rubbish - not as in household waste, but as in stuff we had stored which had been spoiled (boxes of books, mostly, but a few other things).
The landlord is insisting we either return and empty it or pay for it to be emptied. We never had any sort of contract for the garage, the house is not being advertised to let as having a garage, it can't be used in its current state as a garage for a car (although there is enough space for NDN to get his trailer in and out) and we have left it in the same state in which we first got it - better, in fact, as our old stuff is neatly stacked in the back third and it is generally cleaner and tidier. Yes we had free use of it for three years but that has in fact ended up costing us money in real terms due to the items that have been ruined.
If he had been reasonable about other stuff - like the damp in the house - I would consider offering to pay half the cost of a skip, but he has been such an arse since we gave notice that I am tempted to say "it's in better shape than it was when you let us use it, now piss off and leave us alone". But IABU, aren't I? Or is he?