THE results of an investigation into the cause of a massive fire which destroyed a 128-year-old primary school building are "inconclusive" - but investigators are not ruling out arson.

Fire crews left the old Clarendon Primary School building in Clarendon Street at about 2pm today.

They have been tackling a blaze at the school, which was built in 1886, since 6pm last night.

A spokesman said the results were inconclusive and that a fire investigation officer had been to the incident but could not confirm the exact cause of the fire.

Assistant county fire officer Paul Argyle, the fire service's director of emergency response, said: “We were called to a derelict school building on Clarendon Street last night during a time that our whole-time firefighters were taking part in industrial action.

“Emergency fire crew – who are available during periods of industrial action – arrived at the incident within minutes.

“When they arrived, the fire was already well developed and smoke was coming from both ends of the roof with slates and tiles falling off – making the building a dangerous environment."

He said regular firefighters took over the incident later and stayed on the scene throughout the night.

The building was due to be demolished - even before the fire happened - but demolition is now likely to take place more quickly, council bosses said.