William Derby ( 1786 - 1847 ) was a British painter. William Derby s works have been put up for auction numerous times, with realized prices surpassing estimated prices, varying from 134.86 USD for The Incredulity of St Thomas in 2006 to 650 USD for THE YOUNG ROSCIUS (Actor Master William Betty, (b. 1791) in 2006 , based on the size and medium of the artwork.