They were playing Live and Let Die in a shop earlier (yes, very festive). It's always struck me that the elements of the song really don't go together.
You've got the nice melodic bit at the beginning, which is fine.
But then, you suddenly get "Live and let die boom boom", followed by Da da da, da da da, mad drums, dum dum dum dum.
Then the perky "what does it matter to you, you've got a a job to do". More da da da, etc.
Then suddenly. Gentle bit again. Then frantic bit again.
It really does sound like he had a lot of unfinished song ideas which he cobbled together.