I now know that George Duthie died in Glasgow Infirmary. Cause of death was Diarrhoea. It states that he resided in Fortwilliam. Informant of death was A McDonald Brother- In-law. Isabella (McDonald) Duthie died 24 January 1865 in Kilmallie, Forthwilliam. She was 41 years so that makes her birth 1823/1824. Cause of death was Bronchitis. Informant of death was her daughter Christina Duthie. Her parents were Alexr McDonald and Mary McMaster. Obviously her son George could not have been born in 1835.
Any information on Alexr McDonald and Mary McMaster or Isabella and her siblings would be very much appreciated.