Tidying the bathroom this morning I found the spare blades from my original razor. They'd either been stashed, or had fallen into the cleaning products bucket, probably when the man came to fix the boiler the other week. (I have cleaned the bathroom since then, but hadn't poked around at the bottom of the bucket.)
I will follow up on your helpful suggestions from yesterday, but bask in the knowledge I have a good supply to keep me going for now!
Looking at this photograph is a bit odd, I'd never really considered the packaging before. Needing a lie down after beautification, maybe she'd been using my epilator.