Opened front door to go out, and there was a puddle on the door sill (under the closed door) and it hasn't been raining. The children asked why, and I said "I presume one of you dripped there on your return from swimming lessons earlier - can you get some kitchen towel please?"
On wiping it up and smelling it, I realised it was cat's piss
It appears that one of the neighbourhood menaces has now decided to scent mark my front door! The spray on the door and dribbles down was clear on further investigation.
A change from a few years ago when I had to daily pick up the turds (and on arrival home in the dark frequently stood in them and walked them indoors). Fortunately whichever cat that was, which I never traced but have suspicions (based on watching it defecate on the back lawn) has changed habits.
Door cleaned, disinfected, and anti-cat toilet training powder applied all over the front doorstep area. Dead blackbird also removed from back garden.
FFS cat owners, they are your pets, keep them in your premises and not mine.