Complex sentence: Prior to the 1972 Canadian election he accepted an appointment to the Canadian Senate and sat in the body until 1990 when he was appointed Lieutenant Governor of Quebec by Prime Minister Brian Mulroney.
Split into simpler sentences: Prior to the 1972 election, he accepted an appointment to the Canadian Senate. He sat in the body until 1990 when he was appointed Lieutenant Governor of Quebec by Prime Minister Brian Mulroney.