The festive scent of roasting chestnuts could be absent next Christmas because of a double threat to trees, the Royal Horticultural Society has warned.

Britain’s sweet chestnut trees are currently battling the invasive oriental gall wasp as well as a deadly blight which completely wiped out the species in the US in the early 20th century.

The wasp, which has a black body and orange brown legs, produces larvae which feed on the buds of the trees. It was first discovered in the UK in 2015 living in Farningham Woods, near Sevenoaks in Kent and a street in St Albans, Hertfordshire.

But in the past two years it has spread throughout south east England and has most recently been found in Devon, Dorset, London, Reading and Derbyshire.