Complex sentence: He learned his craft in the 1920s with a touring company and later the Birmingham Repertory Theatre, before joining the Old Vic, where he led the company in 1931, succeeding John Gielgud, who had taught him much about stage technique.
Split into simpler sentences: He learned his craft in the 1920s with a touring company and later the Birmingham Repertory Theatre. In 1931 he joined the Old Vic, leading the company the following season, succeeding John Gielgud, who had taught him much about stage technique.