Simply the best! The Swan is a busy City pub on the corner of Leadenhall Market. It's a Fullers tie so Chiswick and London Pride can always be found and they are kept in tip-top condition. Guest and seasonal beers also available.
Alphonso (downstairs in the tiny bar) and Adam (the landlord, upstairs in the lounge) are two of the best barmen I have ever encountered.
Being small, The Swan Tavern is often crowded but you never wait long for a beer and it makes for a good atmosphere.