 The Magdalen Reading was transferred from its original oak to a mahogany panel ( West Indian <unk> ) by unknown craftsmen sometime between 1828 and when the National Gallery acquired it in 1860 . Campbell states that the transfer was " Certainly after 1828 , probably after 1845 , and certainly before 1860 " , the year it was acquired by the National Gallery . Artificial <unk> @-@ coloured paint found in the transfer ground indicates that the change of panel took place after 1830 . The heads in Lisbon are still on their original oak panels . The Stockholm drawing was discovered in a German inventory c . 1916 and is likely of Swedish origin . It was bequeathed by a Norwegian collector , Christian <unk> , to the Swedish National Museum of Fine Arts in 1918 . 
