I hate advertising. I really do. In fact, I've engaged in several arguments over the years about whether or not an advertisement can ever be considered "artistic." My point is that an ad is aimed primarily at getting you to purchase something you probably don't need — if it conjures up any human emotions along the way, it's toward achieving that primary end.
Here's the exception: when you can't buy what's being advertised and only have the option of appreciating the content. Since I don't live in the UK and can't shop at the John Lewis department store chain, I'm going to put my typical hatred of all commercial advertising aside and start crying at this beautiful story of a little boy and his friend Monty The Penguin.
The song in the ad is a cover of John Lennon's "Real Love," performed by Tom Odell. Check out Lennon's version here: