This question is based on the 2011 film of "Tinker Tailor Soldier Spy" with Gary Oldman (which I just watched). As for the 1979 BBC series with Alec Guinness, or the original novel, Ｉ haven't watched or read.
How did Smiley capture Bill Haydon, the mole?
So in the airport Toby Esterhase was scared and revealed to Smiley the address of the London safe house of the Witchcraft operation.
Then Smiley started to lay the trap that eventually unmasks the mole. But how was this done indeed?
Seems Smiley sent Ricki Tarr to Paris, releasing some false information that he knows who the mole is, "to shake the tree".
Then Smiley stand by a phone all the time, someone (who?) informed him that "a full house" is, ie all the suspects gathered at the safehouse.
Then Smiley holds a gun in a room, and Peter outside the building -- where are they? at Alexei Polyakov's place?
So how did Bill Haydon ("Tailor") stepped into the trap? Did he come to Alexei's place to inform him?
Some says Bill and Alexei met at the safe house: "Fearing that he is about to be exposed, the mole meets Polyakov at the safe house where they are arrested by Smiley, revealing himself to be Haydon." But wouldn't that be risky?