Complex sentence: Thomson attended The Hall School, London, England, and Upper Canada College, Toronto, Ontario, and received a BA (subsequently upgraded to an MA) in history from Selwyn College of the University of Cambridge in 1978.
Split into simpler sentences: Thomson attended The Hall School in London, England, and Upper Canada College in Toronto, Ontario. He received a BA (subsequently upgraded to an MA) in history from Selwyn College of the University of Cambridge in 1978.