What's in my Attic? - It's not mice.

Since I moved into my current home I have been having mice infestations every few years always during the winter months.

I live in a Bungalow so it's easier for them to climb up there and make a new home.

This year however it's a little different. The mice have arrived, been exterminated but the noises continue.

I know this as the traps I have laid are still intact and awaiting my visitors to 'eat' the cheese.
However, the 'cheese' remains uneaten.

The noises seem a little heaver than before, the scratching is still there and is always at night but only every 5-6 days.

It's like they are now part time invaders.

I live in the UK, so Racoons and Opossums are not on the agenda as they are not native to my country.

Squirrels? From what I read they are very noisy, with chattering sounds. These guys in my attic seem to wear gags.

Rats? Bigger mice would be after that cheese!

Bats? They also make vocal noises, as I mentioned before.. gags.

So what's in my Attic? Any opinions would be welcome!