So, it appears we have fleas.
We don't own an animal, so I can only assume they're either the leftovers from two years ago when we first moved in, or a workman has tracked them in on their trousers.
I've currently got my third load of washing in the machine, I'm doing a short wash then tumble drying, I've sprayed the skirting with disinfectant in prep before I wipe them all down. We're messy, so I'm going to chuck everything in the garden and then hoover. I have one tin of flea spray leftover which I'll use on the sofas and carpets.
Any further advice?
(It's definitely not bed bugs btw!)