This is similar to the thing that people in the United States, club hopping. In pub hopping, you simply are going from pub to pub in search of the best food and drink as opposed to club hopping where you are looking to dance and find people to hang out with for the night. Pub hopping can be a lot of fun as there are many different pubs and places for someone to go to enjoy all of the different types and styles of foods that London has to offer.
To be able to go and sit and enjoy the company of many of the locals to see what it is they enjoy and what kind of food they are eating to give you a good idea of what it is that they enjoy. Food is something that seems to be universal for all to enjoy and can bring many different people together.