Updated: Police say cause of the fire was deliberate.
The fire seems to have been started in what was the old Nursery/Breakfast club portable classroom, erected on the site a year or so before it closed.
It is thought that the main school building escaped the blaze but we have have been told that over the past few weeks or so the building had been ransacked, with pipes and fittings removed.
St Luke's moved to a new state of the art £5.7m school built upon the old grounds of All Hallows / St Lawrences RC school between Hebden Avenue, Edward Avenue and Weaste Lane last year and has not operated from the old site since.
Police and Firefighters have not yet disclosed the cause of the fire, although they have not ruled out it being Arson.
The flames have now been brought under control and extinguished, whilst firefighters remain attending the scene this evening with three appliances to ensure it is out and also to locate the source and cause of the blaze.
If you have information regarding the fire please contact the police on 101.