POLICE are investigating criminal damage to the roof of a Blackburn vet’s surgery at the centre of a four-year planning row.

The owner says the vandalism fulfils her worst fears about the building of a 30-foot grey metal staircase next to her historic premises in King Street.

Pamela Cartwright was left in despair in May last year when her last-ditch bid to move the structure failed, despite an official ruling it should never have been built.

She feared that criminals and vandals could use the staircase to break into her surgery building.

She was also concerned that someone larking about on the roof could seriously injure themselves.

At the weekend, slates on her main surgery building were damaged by someone jumping on it from the staircase.

There was also damage to door of the top flat of the 200-year-old property, to which it provides access.

Mrs Cartwright, 65, said: “This is just what I have always feared.

“We have had a string of incidents but this is serious criminal damage.

“Something needs to be done. I would contribute to the cost of moving the staircase.”

It remains attached to the building despite a finding by the local government ombudsman that the council was guilty of maladminstration over the structure.

He ordered the council to make an apology and a £1,200 compensation payment.

In 2008, local businessman Russell Heaton applied for planning permission to turn the upper floors of the neighbouring building into six flats.

He proposed a new internal staircase for access, to which Mrs Cartwright agreed.

After intervention by council planners, an external structure was built in 2010 instead, retrospectively approved in May 2013 despite the ruling.

Blackburn MP Jack Straw, who last year said Mrs Cartwright had been ‘outrageously treated’, said: “I shall speak to her, Mr Heaton and the council and see if we can get this staircase fully enclosed.”

A Lancashire police spokeswoman said: “We are investigating an incident of criminal damage and seeking CCTV footage.”

Mr Heaton said: “I have no comment at this stage.”

A council spokesman said: “We will work with the resident to understand and resolve the issue.