How does Jack describe his progression as a thief in his letter from Chapter 43? Where did his family resettle during this time?

Jack describes his training and work for Silas Smith as continuing; he and little Sophina would break into the houses and Sophina was in charge of choosing the expensive plates and silverware to steal. After the summer of 1801, when Jack and Sophina completed 20 of these robbery "errands," he and Mary Bitten and his "adopted family" moved to Islington.