A Kew Gardens volunteer swapped his trowel for the hot seat when he became the first contestant to be grilled by John Humphrys on the history of the botanical gardens.

Quiz-hungry Richard Pyne, one of 600 volunteers at Kew, spent hours learning about the gardens’ 254-year history for his date with the iconic black chair on BBC Two’s Mastermind.

The management consultant from Sheen, who has volunteered at Kew for five years, passed two tough general knowledge auditions to film at the studios in Salford last July.

The 60-year-old said: “It was pretty scary. There were 250 people in the audience, all these cameras, scary lights, scary music and John Humphrys. It was quite stressful.”

Mr Pyne, whose nerve-racking stint on the gameshow will be aired on Friday, January 31, at 8pm, took part in tours, read books and visited temples to clue-up on Kew’s exhaustive history.

The keen gardener said: “I probably chose a very broad specialist subject – someone else chose the Manic Street Preachers which is not quite as in-depth.

“I have been a friend at Kew for about 20 years and the history of horticulture is really interesting and I learnt some fascinating things.”

All 15 of George III’s children were brought up and died in Kew Palace, the first sheep ever sent to Australia were auctioned off in Kew and the refreshment pavilion was burnt down by suffragettes in 1913.

A lady tenant was evicted in the 19th century for running a brothel from Kew Palace and many of Kew’s gardeners were sent on long sea trips or as plant hunters to China, South Africa and the Far East and died on their voyages.

To prepare for his TV appearance, Mr Pyne enlisted the help of former Richmond Council leader Serge Lourie and his wife Julia, who is a guard at Kew.

Mr Pyne, who will stand as Lib Dem councillor for North Richmond in the May elections, said the training helped him prepare for the show.

He said: “Serge dug out a black chair and they fired questions at me. Then the following week we did it again. It is just such a huge subject and a lot of fun.”