Complex sentence: Mario made occasional appearances in oratorio singing at the Birmingham Festival of 1849 and at the Hereford Festival of 1855, and undertook various concert tours in the United Kingdom, but his name is principally associated with triumphs in the theatre.
Split into simpler sentences: Mario made occasional appearances in oratorio, singing for example at the Birmingham Festival of 1849 and at the Hereford Festival of 1855. He also undertook various concert tours in the United Kingdom, but his name is principally associated with triumphs in the theatre.