Is THIS a blackcap? (Got one wrong yesterday!)

I agree with Bob, that one is definitely a Blackcap.
If you get the chance, listen to it as well when you see one, as it will sound completely different to any of the tit species … even I can tell and I'm rubbish at bird song, but many warblers, like Blackcaps are actually quite easy to tell apart by their song, so give it a go and you'll soon start to pick a few up.