Police Scotland has been urged to investigate the removal of a controversial plaque accusing an 18th century politician accused of delaying the abolition of slavery.

On Tuesday, The Herald revealed that the A3 brass panel at the base of the Melville Monument in St Andrew Square had been taken away the previous night, in what Cammy Day, the leader of the City of Edinburgh Council, described as an “improper removal.”

He said that as “caretakers” for the statue, any “works” required the council’s consent, “which was not sought or given in this case.”

Yesterday, a descendant of Henry Dundas, 1st Viscount Melville, claimed responsibility for removing the inscription. 

Bobby Dundas, the 10th Viscount Melville, insisted he and fellow members of the Melville Monument Committee had acted lawfully. They also suggested that it was the council who had "proceeded contrary to law" in multiple ways. 

However, Claire Miller, the Scottish Green Party councillor for Edinburgh City Centre said a "potential crime" may have taken place and contacted police.

READ MORE: Questions for council over slavery plaque on Dundas statue

The inscription on the plaque has long proved contentious. It accuses Henry Dundas of being “instrumental in deferring the abolition of the Atlantic slave trade.”

It goes on to say that as a “result of this delay, more than half a million enslaved Africans crossed the Atlantic.”

It was crafted by a committee comprising of city councillors, Scotland's first black professor, Sir Geoff Palmer, and another academic and was based on Dundas's time as home secretary when he introduced the word ‘gradually’ to a motion by William Wilberforce calling for the immediate abolition of the slave trade.

However, the panel did not include any historians.

The Herald:

That led to Professor Sir Tom Devine, the former Sir William Fraser Chair of Scottish History at Edinburgh University, comparing the task force to a "kangaroo court."

He said they were rushing to judgment "on a complex set of questions without taking the advice of any real expert" and that it was "bad history" to pin the enslavement of half a million people on Dundas alone.

Last month, writing in Scottish Affairs, published by Edinburgh University Press, Angela McCarthy, Professor of Scottish and Irish history and a director at the University of Otago in New Zealand, said Dundas had, if anything, helped steer the way for abolition.

She said the politician, realising that Wilberforce's charge to end slavery faced certain defeat in parliament from powerful slave owners, had tried “to chart a path by which Britain could abolish the slave trade, albeit gradually, starting with an immediate end to slave trading with foreign colonies."

Professor Palmer has rejected Professor McCarthy's evidence, describing it as an “insult to abolitionists such as Wilberforce and Clarkson."

READ MORE: Controversial plaque on Edinburgh Dundas statue removed

Earlier this year, the Melville Monument Committee applied for and received listed building consent to have the plaque removed.

They described the description as “cartoonishly inaccurate."

While that meant that technically the panel could be removed, the final decision was for the landlords of the buildings around St Andrew Square, who are the owners of the monument.

At the time, Councillors suggested that was unlikely. However, the Melville Monument Committee contacted the owners and their lawyers and received no objection when they asked if they could take the plaque down.

They also suggested the local authority may have breached the terms of their sub-lease concerning St. Andrew Square, as they had never properly sought permission from the owners to install the plaque in the first place.

They said numerous freedom of information requests asking for correspondence with the owners returned nothing.

Viscount Bobby Melville said: "We had all the necessary permits, and ensured that the owners of St Andrew Square, who have ultimate authority, had no objection. We acted completely within the law.

"It is the height of hypocrisy for the city to object to the removal of the plaque.

“The city should be concerned about its own unlawful acts. It had no authority to install the plaque without consent of the owners in the first place and continues to defy an order to remove the large signs about the plaque in St. Andrew Square.

“It is in no position to object to the removal of the plaque, which we have done in complete compliance with our legal obligations."

Councillor Miller told The Herald: "I’m shocked to learn this relatively new and very important plaque, which gives the Melville monument its historical context and modern interpretation, is suddenly missing.

"I’ve reported this potential crime to the police, and to Essential Edinburgh who manage the gardens on behalf of the Council, so they can investigate and hopefully return the plaque to its rightful place."

READ MORE: Sir Henry Dundas slavery plaque may be removed after family appeal

Professor Devine said there were now questions for Edinburgh council.

He told The Herald: "From the beginning of this fiasco I have argued that military, political and economic factors rather than anytime actions of any one individual ensured that abolition of the  British slave trade was impossible in the 1790s.

"Professor McCarthy’s forensic and meticulous research on original materials has provided the hard evidence to support that view.

"The plaque was based on nothing other than scapegoating, prejudice and false history.

"It has now gone. When sited in a public place it brought nothing but dishonour to Scotland's capital.

"Now we find out that C Day and his cronies on the Council played fast and loose with due legal process in installing it.

"What are the penalties to be for a local authority which acted in such an egregious  fashion?"

The Council did not respond to requests for comment.

A spokesperson for Police Scotland said: "We received information regarding a missing plaque from a monument in St Andrew Square, Edinburgh on Wednesday, 20 September. Officers will be speaking to the reporter to gather more detail."

Responding to news of the police investigation, Viscount Melville told The Herald: "The Melville Monument Committee  acted well within the boundaries of the law and I, of course, will respond and cooperate as required."