Colleague spreading his stuff on my desk

The interesting part is that he got 'upset' when the things were moved back. Is he trying to train the OP to accept he has two desks and she has none by making a scene when she claims one?

thats's not an excuse. If he needs clearer boundary, HE set them up. He doesn't need a babysitter. There are no excuse for being rude, which he is, and he knows it, after being told repeatedly.

Perhaps a passive aggressive, this is on my desk (mug, papers etc), "do you know whose this is?, it is on my desk"

Is your deskmate called Dwight? A pencil fence is the only option!

Jello-O
see the Office

What's wrong with him!? So disrespectful. Hate that sort of behaviour. Is he a twat in other ways or is this his main way of showing it? It's particularly insidious because it either forces you to take a stand with the risk of making you look like you are overreacting (you're not), or you don't act because you are worried about being seen to overreact.

Had a male colleague who set up a coffee making station directly behind a female colleague's chair for absolutely no good reason. There was plenty of room behind his desk and less room behind hers. Drove her crazy but he just kept on with it. Eventually she (and I) moved offices. We couldn't get out quickly enough.

“Dave, stop putting your stuff on my desk or I am going to bin it.“

Or shout across the office “HAS SOMEONE LOST A GLASSES CASE/ MUG/ ETC AS IT IS ON MY DESK.” If he’s not there send an email saying you’ll deposit it with lost property at the end of the day if no one claims it from you. Then leave the desk and hide the stuff for a couple of hours.

Tell him that any stuff on your desk that is not yours is going to be put in the shredder/bin in future. Can you put a makeshift barrier to stop stuff 'sliding' over as an interim measure?

I would say..

this is my work space
and this is your work space
I don’t go into yours
you don’t go into mine

then end with Nobody puts baby in the corner and storm out 😂

This would drive me absolutely nuts . Not sure what stuff he is putting on your desk but I would be shuffling it before I pushed it back …

Move it as soon as it happens. Do not be smiley, pleasant or apologetic when doing so.

That he wants more space. Ours are tiny so I'd sympathise on that front. If there's no one next to me I definitely overspill. (If there is then I deal with my stuff because I recognise it's not my space.)

For the sheer weirdness value, I’m hoping it turns out that the bloke’s own desk is in a completely different part of the building and he’s not even in her department.

When he went to the toilet I put all his stuff on his desk. He was upset on returning.

So he clearly thinks he has a right to your space. I would take pictures everyday and throw one of his items on the floor when he goes away. And shove the rest back to his table.

This. So set your boundary rock hard and call him out. He’s pathetic.

In my office, the best way to approach this would be to take a trip to a toy store. Buy some little army men ( like the ones in Toy Story). If you can, get some 'Great Escape' style fencing. Then set up your perimeter. All the better if you can find a little sniper one.

Ideally, he'd cop the fuck.on, but given he isn't, making a joke of it that gets others engaged and aware of what's happening helps. Also stops any narrative developing if you're being nit picky or nagging him. Gives you the best shot of someone else calling him out on what he's doing.

Finally this approach has the added bonus of that if he pulls any other stunts in the future, you get to publicly ask him if you're going to have to represent this to him using toy again. This is all about his ego. It's okay to use that to your advantage.

You've tried approaching this in an adult manner. He's behaving like a toddler. Treat him like one.

Op started her thread at 858am this morning. I would imsgine she's probably working now and not able to come onto Mumsnet to supply this vital information.

Put it all back the minute he moves something onto your desk, "Michael we've spoken about this, stop putting your things on my desk."

If it was me I'd tell him "next time it'll be going in the bin, not back on your desk" and then I would just bin it, but I'm petty.

What is his stuff?

pit his stuff in the (clean) bin

Sounds like the equivalent of manspreading to me. I was in a meeting the other day, enough room on a seat for three people but one fella was manspreading so much someone had to pull up a spare seat from across the room!

Or this (after you've explained this will happen). The bag keeps everything tidy and can go under his desk

A bet with someone else in your office to how many times he can do it?

Just swipe it all on the floor.

Explain to him ONCE that you don't want him to do that. Send him an email as well. Next time his stuff will be on the floor by his desk or in the bin. He clearly isn't responding to polite requests not to do it

I would think is mine to use and I will keep it, bin it or whatever. Unless you work from home most of the time, he need a lot of space and there is no drawers available. In that case I will move it back to his.
He may be a dick or just using some space that generally is not been use.
I spread my wings in the office when I know they are not there, sometimes I have to consult far to much books and files and the extra space is handy. I'll clear it up before they come so no problem in my case. They do the same.