How to reply to an early c5 in the London System? I've played the London System for about 3 months and am liking it alot, however I have run across several games where Black played a weird, but good, move early in the opening, c5.

example:
1. d4 d5 2. Bf4 c5

Here, c5 is threatening to take on d4, a key position in the London System.

How does one play with a threatening move such as this with the London System, or what style of play has generally come of this move.

My last question, when Black plays c5, does this generally spell the end for typical London System lines, if played out with typical responses?
How you respond depends on your tastes.

If you like tactical play then 3. e4 is the Morris Gambit. This is basically the Albin Counter Gambit with colours reversed and an extra tempo. It can lead to very exciting play.

If you are more conservative and prefer a quiet life then 3. e3 is the normal move when play can quickly return to more normal lines.