What pest made this hole?

Possibly a bird. We have some tits getting in a similar hole

[i]Possibly a bird. [/i] - Baby Robin?

Wrens like cosy holes for winter nights or might even be scoping out nest sites. Other than that, tits and house sparrows like poking around for insects in eaves and around windows and it looks like there are plenty of those!

Rat on stilts?

Possibly a bird.

Is OP's ex called Louise?

White pliable spheres?

Those are Greater Funnel Web spider droppings, looks like a big colony too.

Can I have your bike?

Those are snowman droppings.

Frosty and his pals have found a new home.  You may also see tiny scarves near the entrance.

Whatever it is I'd be a bit worried that it's had a key cut.

You're all overthinking this. Nothing's trying to get in - it's the pressure overflow valve for the insulation. It bursts if the beads expand too much, to prevent your house exploding.

I suggest just turning your heating down a bit, before you lose a few bricks as it tries to keep up with the expansion rate.

Dwarf Aardvark?

Whatever it is I’d be a bit worried that it’s had a key cut.

Thats just made my day

What pest made this hole?

I doubt that anyone made the hole. It looks like poor quality pointing has crumbled. I suspect that a chilly wood mouse might have jumped at the opportunity of a warm insulated home during the recent cold snap.

Please don't fill the hole..... they are almost as poor as a church mouse

looks like roland - roland doesnt care for working at height regulations - nor asbestosis - ate through my asbestos sofit board. - and my mortar joint in the back door step.

Roland met an untimely end in my burn barrel.

Looks like pointing broken away, or the corner of a brick had a flaw and water and frost have caused it to fall out. Push the loose bits of insulation back in and push some pointing in to seal it up.

@trail_rat name checks out. I am slightly worried about the bum barrel though...

Are they beads or eggs? I once disturbed (I think) a slug nest which looked like that.

Roland met an untimely end in my burn barrel.

Because Kerning, I initially read the 'rn' there as 'm'.

I am slightly worried about the bum barrel though…

Damn it, I really should refresh threads before replying.

Are they beads or eggs? I once disturbed (I think) a slug nest which looked like that.

(the insulation material in our cavity wall)