The mystery of an unidentified tall plant which produced a ten-foot floral stalk after 20 years of inactivity has been solved- after Agatha Christie’s gardener revealed the truth.

Alan Hickman of West Park Road, Sidmouth, used to live in Brixham until three years ago when he moved to east Devon, along with the dormant shrub, which had never bloomed.

While in South Devon he acquired the plant from a landsman at the nearby Agatha Christie “Greenway” estate.

It was never formally identified and never of much interest until it sprouted a huge stalk.

Much to Mr Hickman’s surprise, after his appeal the original gardener at Greenway, known as “Ditsum Geoff”, got in touch and identified the giant.

“It’s absolutely fantastic after all these years that he could tell us what it was,” said Mr Hickman.

“He asked whether it has spiked leaves or smooth- and when we said spiked he told us it was a puya chinesis.

“It’s great to have a proper identification at last, especially from someone who knows the most about it.”

Ditsum Geoff, so named after the village of Dittisham where he lives, has relatives in Sidmouth who told him of the appeal. Besides his positive identification of the Chilean perennial, another seven or eights locals made calls to Hr Hickman with suggestions.

“We’ve become overnight celebrities!” remarked the pensioner.

“We’re quite pleased. It’s obviously sparked a lot of interest as a lot of people around here are keen gardeners.”