Vandals have spray painted political graffiti on Stirling’s historic Smith Art Gallery and Museum.
Each of the building’s four pillars was branded with the message “I still hate Thatcher”.
Police are investigating the vandalism, which has damaged the category B-listed structure in King’s Park. Founded in 1874 from the bequest of the artist Thomas Stuart Smith, the art gallery and museum is a cultural hub for Stirling.
Staff have been left baffled by the graffiti, which was discovered last week.
One worker, who asked not to be named, said: “David Cameron was at the Albert Halls in Stirling last year, so you would have thought they’d have done it there.
“We have no exhibitions that would trigger it and we’re not funded by the government. We are an independent, apolitical charity. We don’t understand why it has happened.”
The vandalism was first seen by staff on March 19 at 10am, shortly before the art gallery and museum opened its doors for the day.
“Someone has stencilled it quick as you like because it wasn’t there when I arrived for work at 8.30am,” said a source at the Smith.
The building, in Albert Place, was listed in 1965, according to Historic Scotland’s website.
The government agency charged with safeguarding the nation’s historic environment has already sent staff to assess the damage.
A spokesman for Historic Scotland said: “We are providing support and advice.”
Director of the art gallery and museum Dr Elspeth King said removing the paint will be a “delicate operation”, adding: “It’s sunk into the stonework.
“It’s had its first clean but it will need a second one to get it off. It’s going to be very expensive.
“The sandstone is very porous and the graffiti is right on the columns. We can’t make a mess of it because it’s the front of the building so we’re grateful to Historic Scotland for their assistance.
“I’m astonished we are the only place that has got this. I don’t know why we’ve attracted this kind of attention. It’s a mystery.”
A police spokesman said: “Police in Stirling are investigating following a report of vandalism at the Smith Art Gallery and Museum in Albert Place.
“Inquiries into this incident, which happened between 7.30am and 10am on Wednesday March 19, are ongoing and anyone who can assist officers with their investigation is asked to come forward.”