DECADES of dirt and grime are being meticulously cleared from one of the grandest and most historic buildings in York.

Penn House, on the corner of Bootham and St Mary's, was built in 1852 by Joseph Rowntree and was sold by Bootham School for what was understood to be more than £1.25 million in 2011 as a family home.

The current owner David Coidan applied for permission to clean the external brick work. The application was originally refused by City of York Council as planners thought cleaning would "radically alter the external appearance of the building in relation to adjacent buildings" and "would fundamentally harm its character and contribution to the wider area".

The decision was overturned on appeal by planning inspector, Keith Turner, who said: "The building might become more visually prominent in relation to its surroundings if cleaned, but that would not be out of character with the original design intention.

"Furthermore, some buildings in the vicinity have already been cleaned and they do not stand out in stark contrast because, whilst the near surroundings have a degree of unity in building style, the street scene is by no means uniform in character.

"The buildings are individual in detail and character. Consequently, I do not consider that cleaning of the appeal premises would be harmful to the character or appearance of the surroundings or the setting of nearby listed buildings."

Bernard Coleman, director of Stoneclean, the Leeds-based company responsible for doing the work, said the degree of contamination of the bricks meant it was a big job.

He said cleaning had revealed a host of original features and returned the building's black soot-covered handmade bricks back to their original golden colour. Mr Coleman said they used diluted acid and super heated steam to clean the bricks.