Complex sentence: In Immigration, Holt continued and expanded the massive immigration program initiated by his ALP predecessor, Arthur Calwell, and he displayed a more flexible and caring attitude than Calwell, who was a strong advocate of the White Australia policy.
Split into simpler sentences: In Immigration, Holt continued and expanded the massive immigration program initiated by his ALP predecessor, Arthur Calwell. However, he displayed a more flexible and caring attitude than Calwell, who was a strong advocate of the White Australia policy.