John Wesley and Miss Bishop, resident near Bath, first struck up a correspondence over Miss Bishop's faith in 1769. By September 1771, Wesley and Miss Bishop had been in regular correspondence about the Methodist Society in Bath and personal affairs.
In this letter, written Sept. 1st, 1771, Wesley informs Miss Bishop of his plans to come to and preach in Bath. He is now calling Miss Bishop 'My dear Sister'; Wesley addressed many friends and well-known correspondents either as 'My dear Sister' or 'My dear Brother'.
See also Wesley's other letters to Miss Bishop in the Online Collection.