London System

The London System is a setup for White built on d4 and an early Bf4, and reaching it through 2. Nf3 and 3. Bf4 is a common move order. Here Black has answered with 2...g6, heading for a King's Indian or Grünfeld-type fianchetto. The Encyclopaedia of Chess Openings has no separate code for the London; this version, against ...Nf6 with ...g6, is filed under A48. White develops the queen's bishop before playing e3 so that it stays outside the pawn chain. The usual follow-up is e3, c3 and Nbd2, with h3 so the bishop can drop back to h2 when attacked and still bear on e5.

Against 3. Bf4 Black nearly always plays 3...Bg7. The alternatives are 3...d6 and the Grünfeld-style 3...d5, after which White scores somewhat better. The two named lines both start 3...Bg7 4. e3 d6 and differ only in where the king's bishop goes. 5. Bd3 follows the standard London scheme. 5. Be2 reflects the view that a bishop on d3 achieves little once the pawn on g6 blocks its diagonal. Black usually castles and then chooses between two plans: preparing ...e5 with moves such as ...Nbd7 and ...Re8, or striking with ...c5, which gives something like a Réti Opening with colors reversed.

A more pointed option is the Jobava London, also called the Rapport–Jobava System. There the queen's knight goes to c3 instead of d2 and eyes c7. It is especially popular against the fianchetto because the bishop on g7 cannot help defend that square. In many London positions Black's sharpest counter is ...c5 followed by ...Qb6, aiming at b2 now that the bishop has left c1. The Poisoned Pawn Variation arises from a different Black setup, 1. d4 Nf6 2. Nf3 d5 3. Bf4 c5 4. e3 Qb6 5. Nc3, where White develops rather than protect the b-pawn.

The games tend to be closed and maneuvering, and the theoretical load is light because White's setup changes little from one Black defense to the next. Critics call it repetitive and short of dynamism. James Mason was the first master to use it regularly, starting in the 1880s. The name comes from the London tournament of 1922, where Capablanca, Alekhine and Rubinstein all played it. Later practitioners include Kamsky, Aronian and Carlsen, and Ding Liren won the sixth game of the 2023 World Championship match with it. It has become very popular at club level. In this position results are almost evenly split and the engine rates the game as roughly balanced.