Grigg was created Commander of the Order of St Michael and St George in 1919 and served as military secretary to Edward, Prince of Wales (later Edward VIII) from 1919 to 1920, accompanying the prince on tours of Canada, Australia and New Zealand.
Grigg was appointed Commander of the Order of St Michael and St George in 1919 and served as the military secretary for Edward, Prince of Wales (later King Edward VIII), from 1919 to 1920, accompanying him on tours of Canada, Australia, and New Zealand.