What goes on behind the closed doors of an artist’s studio? Despite years of study and scientific research, there are still many things we do not know about the production of Old Master paintings.

Close Examination: Fakes, Mistakes and Discoveries investigates workshop practices, collaborations, copies and replicas.

Find out about some intriguing works whose secrets defy even the most sophisticated scientific analysis:

Andrea del Verrocchio, 'The Virgin and Child with Two Angels'
Find out how investigation of this beautiful picture led to a startling new discovery
Follower of Rembrandt, 'An Old Man in an Armchair', 1650s
This painting shows Rembrandt’s profound influence on his contemporaries. But who painted it?
Imitator of Pieter Bruegel the Elder, 'Landscape: A River among Mountains', about 1600
From Italy to the Netherlands and back again – where does this painting really belong?
Studio of Rembrandt, 'The Adoration of the Shepherds', 1646
What light can scientific investigation shed on this intimate nocturnal scene?
Jean-Baptiste-Camille Corot, 'The Roman Campagna, with the Claudian Aqueduct', probably 1826
Find out about a puzzling pigment in Corot’s vivid sketch
After Hugo van der Goes, 'The Death of the Virgin', probably after 1500
Unpick the intricate relationship between this painting and a lost work by Hugo van der Goes
Attributed to Albrecht Dürer: 'The Painter's Father'
Was this portrait, presented to Charles I, an original by Dürer, or a copy?
Angelo Caroselli, 'The Plague at Ashdod (after Poussin)', 1631
Find out about the intriguing origins of this faithful Poussin copy
Italian, 'A Dead Soldier, 17th century
Who painted this powerful depiction of a dead soldier?
Frans van Mieris the Elder, 'A Woman in a Red Jacket feeding a Parrot', about 1663
Two nearly identical paintings exist – can you spot the difference?