In the last couple of weeks, I noticed a hole just underneath my front door. TBH I thought I just hadn't noticed it before (powers of observation not great...) not that it had just appeared.
Anyway tonight my sister came to visit and as soon as she walked up the drive she said 'what's that hole'. So I'm now thinking it's new. And I'm thinking has a rat made it 
If it is a rat I could obviously seal it with some expanding foam but if there's a nest and they die, won't it smell horrific?
Fwiw there have been sightings of rats in our street. I saw one at the end of my back garden last summer but none since.
Any advice?