Complex sentence: His first performance was as Orlando in "As You Like It", followed by "Love's Labour's Lost", in which he starred alongside Osmond Daltry, who later became a successful theatre manager and an instigator of Hordern's professional acting career.
Split into simpler sentences: His first performance was to be Orlando in "As You Like It", followed by "Love's Labour's Lost", which also featured Osmond Daltry. Daltry later became a successful theatre manager and encouraged Hordern's professional acting career.