Neighbour taking over our cellar space

[stretto]

How should we deal with this and how concerned should we be?

We have a upstairs flat conversion which we let out. The downstairs neighbour is the letting agent for the property and lives there.

There is a small cellar space which is ours. The neighbour has had permission to use some of it (not in the title deeds, just an act of goodwill from us). There are laundry facilities in the space but the neighbour, in capacity as letting agent, has told the tenants they can't use the laundry, and they have to go to a laundrette. He has now put a combination lock on our cellar space without asking us, and we had to ask him for the entry code, i.e. we were locked out of our own space.

He has put his own filing cabinets in the space, which in principle is OK, but the combination lock issue is worrying.
We have been allowing him access for three years. Is it time to put a stop to it?

Yes.

Succinct!

The problem with doing someone a favour is that there inevitably comes a time when they overstep the mark. As they say, “no good deed ever goes unpunished.” I’d remove the combination lock and return it to him together with a letter revoking your permission for him to use the space and requiring him to remove his filing cabinets and other belongings. As he lives in the building 24 hours would probably be reasonable notice. I’d then put my own lock on the door.

Why did you ask your neighbour for the code to the lock rather than tell him to remove the lock?

Succinct!

I know. Most unlike my usual posting style.

But honestly it seems quite simple. You are doing him a favour and he has now overstepped the mark and is treating the space as if he owns it. It will only get worse and you need to take back control.

Why are you letting him make your property less attractive to your tenants (lack of laundry)? I would find this really unacceptable and a big indication that he is incapable of acting properly as a letting agent for you

Yes. Not only is he being a cheeky bastard, by allowing him to have a lock you are sending the message that he has some right to exclusive use.

Someone who is less rusty on their law would be able to clarify if you're actually granting rights, but I'd definitely call a halt in any case.

Thank you so much for all your replies. We have decided we will book a tradesman to come in and do some maintenance work, and that the neighbour will have to remove his filing cabinets to allow access, then we will change the locks and offer the tenants access to the laundry. Thank you all again.
Any thoughts on him gaining legal access would be most useful. For instance, if we sold the flat, is there a risk that an incoming buyer's ownership of the cupboard could be compsomised, or that they might find they had joint ownership with the neighbour, instead of sole ownership?

You have no problem provided the deeds to your property include the cellar space. Your neighbour could go to court for a Declaration of ownership / shared ownership but he'd lose the case and it would cost him money - he doesn't become owner of your basement / car / lawn mower or whatever just because you're kind enough to let him use it.