GPS played most of his best games in partnership with Ian Scott Smith. He was captain of his country in 1925 when Scotland won the Grand Slam for the first time. He had a distinguished war record being awarded the OBE in 1943 and promoted to Brigadier in 1945. After the war he resumed his business career in the investment management field. He was active in charity and was awarded the CBE for his work on behalf of the Royal Greenwich Hospital. A strong supporter of the Clan Macpherson Association and a generous benefactor of the Clan Macpherson Museum, he presented these two rugby caps.
On St. Andrew's Day 2002, GPS Macpherson was one of the first fifty names admitted to the Scottish Sports Hall of Fame in the National Museum of Scotland in Edinburgh.