At the present moment the London System is becoming increasingly popular at the top level - even in ‘classical’ tournament games, although it’s much more often seen in rapid.
Currently the top players who use it most frequently are American Grandmaster Gata Kamsky and Russian Grandmaster Boris Grachev, while other top players occasionally have it in their repertoire, usually using it as a surprise weapon. Among them are Magnus Carlsen, Vladimir Kramnik and others.
Also a great contribution to this system came from the French Grandmaster Eric Prie, who plays it in a very original and active manner.
Nikol Sedlak: "One year after the first book was published, I decided to round out our white repertoire to include Black’s response 1...Nf6. I have tried my best to write this book in the same spirit as my first one, meaning that openings are explained through analysing complete games, putting the accent on typical plans and pawns structures arising in these kinds of positions. Only a small part of the book contains some forcing positions that need more in the way of ‘memorising’. This repertoire which I am recommending is a good weapon against very sharp and well-prepared opponents."
Nikola Sedlak was born in Subotica (Serbia) in 1983. His best rating is 2605. Grandmaster since 2003. Winner of many open tournaments. He started to play the London System in 2005 and plays it with big success even nowadays.