Complex sentence: Alexander Mattock Thompson (9 May 1861--25 March 1948) was a German-born British socialist journalist, from the 1880s, who became an important librettist of Edwardian musical comedies in the early 20th century.
Split into simpler sentences: Alexander Mattock Thompson (9 May 1861--25 March 1948) was a German-born British journalist and dramatist. He became an important librettist of Edwardian musical comedies in the early 20th century.