Conservators at Bristol Museum led a project to clean several large-scale wall paintings in advance of M Shed opening. Paintings Conservator, Carolyn Lamb, said: 'Time and decay affect all museum collections and the effect can be so bad we can know we have an object yet not be able to see what it is.'.

Number 15, Queen Square, was a fashionable Bristol town house and its hall and stairwell were decorated with wall paintings of classical heroes. Grace Brothers (flour and grain merchants) donated the paintings to the museum in 1907 in advance of the house being demolished for redevelopment. Before they were cleaned Carolyn said 'all you could see were vague shapes through the thick dirt and brown varnish.' A major challenge that faced the team was the sheer size and weight of the objects: each painting weighs about 1.5 tonnes each. They are still attached to the original plaster and lathe wall-structure, which was just as important to protect as the paintings themselves. This meant that as well as specialist conservators, the team necessarily included structural engineers who attached the paintings to special frames that would allow them to be moved.

Now that work has been completed, the images on the walls can be studied more closely by visitors to M Shed but also by art historians who will try to reveal who painted them.