Unfortunately it was written for the commercial, and as far as I've found there's no "complete" version other than what is shown.
Benjemen Hornet!
Tony Bennett
womack
duffy
? Dani Klien
Natasha Beddingfield
The Skids, Into The Valley.
Hellen O'Connel & Dean Martin
Guns N' Roses
Shirley Bassey
Lenka sings in the DFS advert (I think? ? ?) :) :)
The singer who sings "Stand By You" in the Nationwide advertisement is Rachel Platten.