Complex sentence: Sullivan sold the score to Metzler in 1878, but bought it back again in 1880 and would mention, in an 1897 letter to his secretary, Wilfred Bendall, having part of the score in front of him when composing "Victoria and Merrie England".
Split into simpler sentences: Sullivan sold the score to Metzler in 1878, but bought it back again in 1880. He also mentioned, in an 1897 letter to his secretary, Wilfred Bendall, having part of the score in front of him when composing "Victoria and Merrie England".