Complex sentence: In 1922, he and his mother moved to Montreal in Canada, where she was hospitalised for a serious chest infection and he was brought up by his Aunt Leslie and her husband Bruce, a wealthy stockbroker.
Split into simpler sentences: In 1922, he and his mother moved to Montreal in Canada, where she was hospitalised for a serious chest infection. He was put under the care of his Aunt Leslie and her husband Bruce, a wealthy stockbroker.