Complex sentence: Lord Oliver married twice, firstly Mary Chichester Rideal in 1945; after her death in 1985, he married secondly Wendy Anne Lloyd Jones (née Harrison) in 1987.
Split into simpler sentences: Lord Oliver married twice, firstly Mary Chichester Rideal in 1945. After her death in 1985, he married secondly Wendy Anne Lloyd Jones (née Harrison) in 1987.