His maternal uncle was Thomas Leverton (1743–1824),[1] a distinguished architect sometimes credited with the south range of Bedford Square in London.

[2] Donaldson travelled overseas after leaving school, obtaining a clerical job with a merchant on the Cape of Good Hope before volunteering for an expedition to attack the French-controlled island of Mauritius.

Once back in London, he was employed in his father's office, before visiting Italy and Greece to broaden his experience, travelling with John Lewis Wolfe and W. W.

He designed the institute's Mycenean lions medal and the motto ‘Usui civium, decori urbium'.

[8] Donaldson died in Upper Bedford Place, Bloomsbury, and is buried in Brompton Cemetery, London.