Devon and Cornwall Police think the fire may have been started deliberately.
Detectives are appealing for anyone who may have seen any suspicious activity in the area either in the late evening of Sunday 12th May or the early hours of Monday 13th May.
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Helen has the forecast for Devon, Cornwall, Somerset and Dorset.
Helen has the forecast for Bristol, Wiltshire, Somerset, Gloucestershire and Dorset.
Figures obtained by ITV News West Country show that drivers in Plymouth spend over two working days a year stuck in gridlock in the city.