 The earliest depiction of the arms was thought to be about 1590 , in a document held by the College of Arms , which refers to the stags appearing on a blue ( in heraldic terms , azure ) background but subsequent examination of this document by Peter Donoghue , Bluemantle Pursuivant shows that the arms were added c.1680 . The first known appearance of the arms is therefore on John Speed ’ s Map of Oxfordshire in 1605 with a blue field . The green field made its appearance by 1619 in an armorial quarry painted by one of the Van Linge brothers . The green background became generally ( but not universally ) used by the 1730s , still appearing as horizontal hatchings indicating azure were in use on bookplates for the college library as late as 1761 . 
