Remember the last action in Chapter 44 - Pip receives a note from Wemmick telling him not to go home. Acting on this note, Pip goes and spends the night at a grubby inn and the following day he goes to find Wemmick. Wemmick explains that he has learned that Compeyson is trying to catch Magwitch and was watching Pip's rooms. Wemmick also passes on Magwitch's new whereabouts because Herbert has moved him to Clara's house. Wemmick therefore helps Pip by passing on information relevant to Magwitch and Pip's attempt to hide him.