Complex sentence: From 1898 to 1913, as the musical director of London's Alhambra Theatre, he composed, arranged and conducted the music for approximately 30 ballets and scenas.
Split into simpler sentences: From 1898 to 1913, he was the musical director of London's Alhambra Theatre. There, he composed, arranged and conducted the music for approximately 30 ballets and scenas.