THIS group of 13 paintings in the collection at Glasgow's prestigious Kelvingrove Art Gallery and Museum was commissioned to wow the 19th century Scottish nouveau riche by depicting Bible stories and ancient history.

Yet the money that paid for the artworks' creation tells a much darker story: one of slavery, empire and decades of economic exploitation.

The collection of 13 oil paintings, once owned by a prominent Glasgow socialite and now in the keeping of Scotland's most visited museum, were paid for with the proceeds of slavery on Caribbean plantations, an investigation by the Sunday Herald has uncovered.

The paintings, including an Old Master which is currently on public display, have been housed in Kelvingrove since being donated by Cecilia Douglas, a wealthy Glaswegian widow, on her death in 1862.

In 1794, at the age of 23, Douglas was married to a prominent slave-owner twice her age. After her husband's death in the early 1800s, Douglas used his fortune, earned from the slave trade, to build up an impressive art collection which she eventually left to the people of Glasgow in her will.

A new database of Britain's historical legacy of slavery shows Douglas received the equivalent of £3 million in compensation payments from the British government for her share of 231 slaves on the Caribbean island of St Vincent when the practice was abolished.

The collection's murky origins have led to calls for the museum to come clean about the paintings' past.

Bonnie Greer OBE, who sits on the British Museum’s board of trustees, said: "I certainly feel that information should be available to the public concerning any work's provenance, especially in relation to slavery and other crimes against humanity."

Asked whether the pieces should be taken down or sold, she said: "That's complicated. But if and when knowledge such as what the Sunday Herald has uncovered is known, then the public, if they want, will decide in concert with the museum about how things go forward. Let your readers know. Let them take the next step."

The collection under scrutiny is made up of oil-on-canvas works mainly created in the early 1800s. They include one Old Master – Still-life: Herring, Cherries And Glassware by Willem van Aelst – plus three original works by 19th century artists and a number of Old Master copies. Works by van Aelst can sell for more than £100,000.

It is believed Douglas bought, and perhaps commissioned, many of these Old Master copies during a Grand Tour around the Continent in the 1820s.

Emanuel von Baeyer, a dealer in Old Masters, said: "It was very much the taste of the time to buy and hang copies of Old Masters. It is typical of the nouveau riche taste that they would decorate the house with what are called 'conversation pieces'.

"You have a painting that has a historic subject, or a well-known copy of an Old Master, which you then stand in front of and have a conversation about. The aim is to decorate your house in a very rich manner but also to walk around and talk about Julius Caesar and other people."

Slavery conditions on the Mount Pleasant estate on St Vincent were brutal. Large gangs of slaves would spend much of the day digging holes for the sugar cane and constantly weeding the plantation, with women not spared such physical labour.

Dr Nick Draper, part of the University College London team behind the new database, explained how slave colonies like St Vincent faced "demographic catastrophe" in the 1800s because of a ban on importing new slaves from oversees.

He said: "The population simply was not reproducing itself. The mortality rate is very high and the birth rate is very low. The slaves die off because they are being worked in very difficult conditions very hard with inadequate nutrition."

Douglas was not the only Glaswegian profiting from Caribbean slave colonies in the early 1800s. Scotland itself benefited disproportionately from slavery compensation – Scots made up 10% of the British population but 15% of the slave owners who got payments, with Glasgow getting much of the cash.

The early 1800s have been called Glasgow's Golden Age of Sugar, as Glasgow University's Stephen Mullen explained: "After the American War of Independence finishes, Glasgow's tobacco monopoly ends. So from then on they just focus on the economies that are under British control. Also, the Haitian revolution in 1791 knocks out their biggest sugar competitor, so for a very short period Britain monopolised sugar imports."

A spokesman for Glasgow Life, which runs Kelvingrove Museum, said: "Like every other major museum service, Glasgow's collection contains items which were donated to the city and may have been purchased through the proceeds of slavery.

"The collection reflects the whole history of the city and doesn't airbrush the mistakes of the past."

THE WORKS OF ART

Still-life: Herring, Cherries and Glassware, Willem van Aelst, 1680, above

A marble tabletop draped with a curtain supports a silver plate carrying a herring, cherries and wineglass.

View of the Roman Forum, Gaspare Gabrielli, 1824

The Italian landscape setting shows the ruined columns of the Temple of Vespasian the temple of Castor and Pollux.

The Death of Julius Caesar, Vincenzo Camuccini, c1825-29

Caesar is attacked in the Senate by a group including Brutus and falls under their daggers.

Roman Women Offering Their Jewellery in Defence of the State, Vincenzo Camuccini, c1825-29

A mass of robed women gossip as they line up.