George Chalmers ( 1720 - 1791 ) was a British painter. George Chalmers s works have been put up for auction numerous times, with realized prices surpassing estimated prices, varying from 48.17 USD for The Life of Mary Queen of Scots, in 2004 to 1351.57 USD for Portrait of Roger Simpkinson in 2012 , based on the size and medium of the artwork.