Sir John’s father was Sir Adam Forrester (Forstar) who was Chamberlain to Queen Annabelle Drummond wife of King Robert III. Sir Adam "acquired the estate of Crostorfyn from Gilchrist More, brother to William More of Abercorn, in 1376." (54) (The Mores or Mures of Abercorn were related to the Mures of Rowallan and cousins to Queen Elizabeth Mure the 1st wife of King Robert II.)