Can anyone identify this, please?

[battybobo1]

In our kitchen, along the join between walls and ceiling, there are little brown patches. DH has cleaned it off a few times but it keeps coming back. If you run your finger along it, there is a powdery residue on your fingertip.

There are no patches anywhere else in the kitchen, or in other rooms. We are assuming it is some sort of insect, but haven't spotted one.

Can anyone tell us what it is, please?

Is it not a leak?

I don't think so. There are little patches along all 4 sides of the join between ceiling and wall. It doesn't feel damp.

When I said there were no patches anywhere else in the kitchen, I meant that it's not in the middle of the ceiling or walls. It's just in the join.

What is on the other side of the wall?

And above it?

Well it's around the whole edge of the ceiling, so some is an outside wall, some the lounge, some the hall and then above it is bedroom bathroom.

Mine looked similar to that when I had an overflowing gutter. Odd that it's all round the ceiling!

Could it be iron oxide stain?