Look who I've just met in the garden.
I'm fairly sure that it's a field vole, if only because these are reckoned to be the commonest mammal in the UK. The Mammal Society suggest that there are 75,999,999 others.
So where are they all? I mean, the UK population of humans is only 64.1 million.
The answer is, that if you want to win at Hide-and-Seek, don't play it with a field vole.
I am pretty sure (from its surprisingly slow efforts to outrun me, compared with mice which almost break the sound barrier), that it is heavily pregnant. So, more field voles then.