The portrait of John Glassford and his family, painted in the 1760s by Archibald McLauchlan, is Glasgow Museums' only painting of a Glasgow tobacco lord. It has graced many books, magazines and websites illustrating the importance of the tobacco trade to the development of Glasgow as an international centre of trade and industry.

There were also some intriguing stories about the portrait which were crying out to be investigated further. The most popular concerned the figure of a young black man that was believed to have been painted over or deliberately obscured during the 19th century anti-slavery movement, thus painting out Glasgow merchants' involvement with slavery. The other story was that Glassford had his third wife's face painted over his second wife.

For 2007, the 200th anniversary of the abolition of the slave trade in the British Empire, Glasgow Museums decided to take a closer look at the portrait and find out more and perhaps discover Glasgow merchants' links with slavery. 'The Glassford Family portrait – a hidden legacy' tells the story of how Glasgow Museums staff went about finding out if there was any truth to this, and what they discovered in the process.

At the end of 2006 painting conservators Polly Smith and Lorraine Maule began to examine and then clean the painting, revealing the young black man standing behind John Glassford, a visible reminder that wealthy merchants and aristocrats had black slaves as a status symbol. They also found evidence that a figure of a woman had been painted over.

The painting conservators will continue to work on the painting in the gallery as part of the exhibition through Sunday 2 March 2008.

John Glassford (1715–1783) was one of the main merchants popularly known as the 'tobacco lords' who became very wealthy by trading in tobacco grown in the American colonies with slave labour. He owned several trading stores and plantations in Virginia and Maryland. The portrait shows his family and personal slave in the sitting room of his Glasgow home, the Shawfield Mansion, now the site of Glassford Street. -- www.glasgowmuseums.com