General Ideas and Options for the London System?

Everything you can tell me about the London System from Ideas to continuations, attacking options, weaknesses, and strengths. Everything and anything. 

https://en.wikipedia.org/wiki/London_System

 Also explaining why certain lines differ

London material that is possibly of interest:
https://web.archive.org/web/20140627074459/http://www.chesscafe.com/text/hansen85.pdf
http://www.gambitbooks.com/pdfs/Win_with_the_London_System.pdf

https://www.newinchess.com/media/wysiwyg/product_pdf/9035.pdf

https://www.newinchess.com/media/wysiwyg/product_pdf/7619.pdf

https://www.newinchess.com/media/wysiwyg/product_pdf/7767.pdf
https://web.archive.org/web/20140627100246/http://www.chesscafe.com/text/hansen139.pdf
https://web.archive.org/web/20140708093403/http://www.chesscafe.com/text/tips.pdf

https://www.newinchess.com/media/wysiwyg/product_pdf/7656.pdf
https://www.chess.com/article/view/the-perfect-opening-for-the-lazy-student
and there is also First Steps: The Colle and London System.
https://www.chess.com/article/view/how-to-understand-openings
Some places are now selling a set of London System DVDs by GM Damien Lemos. I understand that there is also a GM Simon Williams DVD on the same subject.

Put the London system counter

Here are some basic tips you may like:

• The London is an opening system where White can make the same first moves against almost anything Black throws at him. The moves are: d4, Bf4, Nf3, e3, c3 Be2/d3 followed by O-O.

• The bishop on f4 is an active piece and, in most cases, you want to spend a move or two to save it. For example: Black may have the possibility of ...Nf6-h5xf4 after White has played Nf2-f3, blocking the d1-h5 diagonal. So consider spending a tempi on h2-h3 to give the bishop a retreat square.

• ...Bf8-d6 is another standard idea to exchange Bf4. Taking on d6 immediately is oftentimes not recommended. Instead, you should drop bishop on f4 to g3. If Black is so inclined to exchange, you can recapture with hxg3, developing your rook!

• You must prepare for the annoying ...Qb6 (threatening ...Qxb2) when playing against ...d5-variations. The most responses are to Qd1-b3 and to sacrifice the pawn for development and piece play.

• If given the chance, attack on the kingside. The usual opener is Ne5, but the follow up varies depending on the position. If White hasn’t castled yet, he can even initiate a pawn storm like in the following game:

• The other standard plan for the London player is to break in the center with e3-e4. Capturing on e4 (...dxe4) gives White’s pieces more freedom and cedes the center. But if Black doesn’t capture on e4, White will play e5 gaining kingside space and, possibly, an attack.

• If Black tries to copy White, out of confusion or as an attempt to annoy you: Ex: 1.d4 d52.Bf4 Bf5 3.e3 e6 4.Bd3 Bxd3 5.Qxd3 (White has two developed pieces while Black has none) c6 6.Nd2 Nf67.Ngf3...Expect a good game!

For your viewing pleasure, check out this fantastic game by Carlsen, displaying sound but active chess culminating in a winning attack.

As for variations and defenses you need to prepare against, you will want to focus on set ups instead. Preparing for specific move orders are tricky as transpositions abound in the London System. Here are some Black set-ups to look into:

• ...d5 without c5
• ...d5 with ...c5
• Queen’s Indian Setups (...b6 and ...Qb7)

When facing the above set ups, White’s strategy is to not to commit to anything, strengthen his d4-point with c3, develop the queen, castle, and only then get active. How he executes this strategy, however, depends on the specifics.

If you have the time, check out this free guide on the London System (which covers the set-ups above and more): https://www.chessable.com/book/short-sweet-the-london-system/5774/

The book uses spaced repetition to “burn” the ideas and moves into your long-term memory, which I’m a fan of.

Back to Black setups…

• ...g6 setups - You can try Nf3, e4, and Qd2 (intending to exchange the bishop on h6), giving you a bigger share of the center and easier development.

• Benoni-type setups (...Nf6 followed by ...c5) - Play d5 to gain space then develop.

Well, this reply has gotten longer than expected so I’ll leave it at that. I hope this helps.