Haha! This is our neighbour too! We find it funny. He lives there with his wife and adult son.
We built a summerhouse during the first covid lockdown and painted it a certain colour and then painted our shed the same. Within a month, our attached semi detached neighbour painted his the same colour. Within a few months, his neighbour and their neighbour painted their sheds and summerhouse the same colour. So 3 other houses did the same colour!
We then started working on the garden. Had a new patio laid with steps and walled flower beds. Next door was in their bedroom window watching at times, now they have the same slabs as us. We have seen them with their visitors in their garden leaning over our fence, pointing things out that we have done and then it appearing in their garden within months. I have planted a lot of shrubs down both sides and along the bottom, so we will eventually have a private garden.
When I wash my car, he comes out and washes his. When I jet wash the drive, he follows with his jet washer and does his. When I cut the grass, he cuts his. If I go out to wash the windows, he follows with his bucket. I went out the once, to do some weeding in a flower bed I put adjacent to the fence we own between us, and he came with his spade and started doing the same right in front of me the other side of our fence.😂 I started growing vegetables and now he has a vegetable patch too.
We have now painted the lower half of the back of our house a colour because we are going to get a glass roofed shelter installed over the patio in the spring. We will see if he follows. He hasn't yet because since we did that, the weather turned so he hasn't had chance to.
At first, we were like "what on earth is going on?", but now we have got used to it and to be fair, we would rather have him as a neighbour than a bad one.
Just to add, we never really spoke to each other other than to say hello, now he comes round with chocolates every christmas and Easter, so we now have to do the same and give him some in return. 😂
He is harmless and it's actually nice that they like what we have done to our garden so much they want to have the same. Not sure how he will spend his time, when his view is blocked by the shrubs. Guess we will have to wait and see.