Almost 150 years after he died, ending his life exhausted and depressed at apparent failure, the Irish artist Daniel Maclise has been vindicated: it was London filth, not his technique, which tarnished his reputation and the surface of his two masterpieces, the biggest paintings in the Palace of Westminster.

“It is a tale of horror and disappointment,” said Malcolm Hay, curator of works of art in the palace. “The one thing I hope we can do is to turn back the clock and give poor Maclise his due.”

The unveiling of the two gigantic paintings in 1865 – 100 sq metres, heaving with soldiers and sailors, guns and horses, depicting the meeting of the victorious generals Wellington and Blücher after the battle of Waterloo, and the death of Nelson at Trafalgar – should have been the greatest moment of of the artist’s life. Each had taken a year to paint and years of research. Instead his work was greeted with moans about the cost and shock that the surface of the earlier painting was turning black.

A large conservation project has now started to improve on at least 30 previous attempts to make the paintings look better. Conservators are gently removing grime-infused wax and discoloured varnishes as well as the soot and dust trapped in the layers. Where the wax cannot be cleared without causing further damage, gentle warming to melt it slightly can cure the white bloom which makes the paintings even murkier. Read more