Here are my impressions:
Robbie Williams (who isn't known in the US, and therefore not too familiar to me) reminds me of Norman Wisdom. My mother kept telling me how daft he is and what a great sense of humo(u)r he has, but those silly faces at the camera just looked like well, Norman Wisdom. (I realise I'm really aging myself with this, but Google him and you'll see what I mean.)
Cliff's voice isn't what it used to be. And he's either going deaf or he can't sing on key. Overall, not very impressed.
Madness - were ace. I've always liked them and they sounded every bit as good as they did back in the day!
Grace Jones - not at all sure why she was there, nor why she was hula-hooping. I like her stuff, but would definitely have had her sing "My Jamaican Guy", which has a little more oomph!
Sir Elton - Hmmm. Giving him lots of credit for having just had pneumonia.
Sir Tom - (is he a Sir?) - whether you like him or not, his voice sounded fantastic. Strong, and in key. AND (Cliff) he didn't move around and otherwise jiggle his old-man bits.
Sir Paul - you can't go wrong with the Beatles' library of songs, but his voice was a little hoarse. However, he sounded like he had a cold at the end when he could hardly speak, so once again, I'll give him a break.
And Lenny Henry? You don't interrupt Rolf Harris (who should be a Sir if he isn't already) when he's half way through the 2nd verse of Two Little Boys. I realise Lenny was probably obeying the little voice in his head piece, and the Queen had a beacon to light, but -
DON'T EVER DO THAT AGAIN.