Complex sentence: The intrepid John Fraser died in London, Sloan Square, Or he died in Glasgow--the family account of his death place (and the Hogg article) differs from the accounts published in Brendel and Ward.
Split into simpler sentences: The intrepid John Fraser died in London, Sloan Square, Or he died in Glasgow. The family account of his death place (from the Hogg article) differs from the accounts published in Brendel and Ward.