A MASSIVE 10-mile stretch of the South West’s most vital link road to London was forced to close for eight hours last week as fire crews battled a raging blaze on a hay lorry.

And now Devon and Somerset Fire and Rescue Service has revealed what it believes to be the cause of the fire.

The fire service rushed to the scene on the A303 on Thursday (April 25) as a HGV carrying 12 tonnes of hay went up in flames.

Two fire crews reached the scene at the border between Somerset and Devon at around 1pm.

It wasn’t until eight hours later, at around 9.10pm, that the stretch of the A303 was reopened.

Following the fire fight, a spokesman for the fire service said the most likely cause of the inferno was a discarded cigarette.

They said: “The fire started in the hay. The mostly likely cause is a discarded cigarette or something similar.

“The lorry driver did really well and was able to detach the trailer so that only half the hay was affected.

“If it was a cigarette, it would have most likely come from another vehicle.

“We left the scene at 6pm, at which point the lorry would had to have been recovered.

“100 per cent of the lorry’s load was destroyed. There was 80 per cent damage to the lorry bed and slight damage to the lorry cabin.

“A lot of the hay had to be left in the field next to the highway.”

Highways England was forced to close the road all the way from the A358 Southfields roundabout to the junction with the A30 near Yarcombe - a 10 mile stretch.

In total, six fire crews were called to get the fire under control, including special appliances.

Two fire engines and a water carrier were initially sent to the scene.

The fire service spokesman said: “Crews set about extinguishing the fire involving six tonnes of hay on main vehicle, with a trailer carrying a further six tonnes being detached to prevent fire spread.

“Police were required for full road closure.

“Crews requested additional crews and another water carrier to assist with firefighting.

“Crews were at work with a farmer’s telehandler removing hay to prevent fire spread.

“Compressed air foam was also in use to extinguish the fire.”

Highways England said there was damage to the road surface and a road sweeper was asked to assist with carriageway clean-up.

The cause of the fire is being treated as accidental.