A 24-HOUR cordon put around a fire at a Wooburn Green farm had to be extended as firefighters discovered several cylinders of dangerous chemicals.

Police set up a 200-metre exclusion zone, which included evacuating three homes and closing roads, around a workshop, pictured below, at Orchard Farm in Juniper Lane after a fire broke out at around 1.30pm last Thursday.

Firefighters were unable to enter the building, which was well alight when they arrived, but set up two free-standing jets of water, called ground monitors, to cool an acetylene cylinder which could have exploded in the heat.

Under Health and Safety Executive guidelines, the cylinder had to be cooled for 24 hours. This period was extended to 36 hours, until Saturday morning, after a second cylinder was discovered at 11pm on Thursday night.

Beaconsfield fire station manager John Bull said: "We had a workshop fire involving various cylinders - oxygen, argon - but the main risk was acetylene.

"Initially our information was that an acetylene cylinder had already exploded. Further investi-gations identified that it still had the potential to explode."

Acetylene is a substance used in welding. Two joined canisters, one containing the chemical and the other containing oxygen are fed through separate lines to a welding torch.

Relief crews from High Wycombe, Beaconsfield, Gerrards Cross, Great Missenden and Marlow took it in turns to monitor the workshop until it was considered safe.

Fraser Pearson, communications manager for Buckinghamshire Fire and Rescue Service, said: "If acetylene cylinders get too hot they will explode and they literally go off like fire bombs and can be very destructive.

"Neighbours reported hearing a series of explosions, but we don't think any more cylinders have exploded since then. They may have heard loud bangs of objects falling in the fire. No one was in the workshop at the time." The workshop was completely gutted by the blaze.