When I was out walking the other day, I could hear a number of Long-tailed Tits in the trees above me.
I noticed one (see below) that was searching for food under bark and lichen.
Then I could see another one that had been successful and had caught a large green caterpillar.
(at a guess, probably a Meadow Brown caterpillar)
It was quite a big caterpillar compared to the size of the bird, but the bird was using his perch on which to beat the ill-fated larva.
I don't know the outcome to this story unfortunately, but I didn't fancy the caterpillar's chances.
Looking on from a secluded spot was a female Blackcap.