Complex sentence: The theatre was opened in 1867 as the Royal Colosseum & Opera House by James Baylis who also ran the Milton Colosseum Music Hall at Cowcaddens Cross, and had opened the Scotia Music Hall, later known as the Metropole, in Stockwell Street in 1862.
Split into simpler sentences: The theatre was opened in 1867 as the Royal Colosseum & Opera House by James Baylis. Baylis also ran the Milton Colosseum Music Hall at Cowcaddens Cross, and had opened the Scotia Music Hall, later known as the Metropole, in Stockwell Street in 1862.