TORQUAY (AFP).- Throughout her prolific career, mystery author Agatha Christie killed off hundreds of characters by bullets, daggers, even a blow of the cleaver. But her ultimate weapon, and the one she was most fond of, was poison. 

"They can't be poisoned every time but I am happier when they are," the author supposedly once said, according to her publisher HarperCollins.

It was a predilection no doubt linked to her encyclopaedic knowledge of the subject, said chemist Kathryn Harkup, author of "A is for Arsenic: the Poisons of Agatha Christie".

Harkup was speaking about Christie at a festival dedicated to the novelist in her hometown of Torquay, southwest England, which runs through Sunday.

The genteel seaside resort is celebrating the 125th anniversary of her birth. Christie died aged 85 in 1976.

Before launching her literary career, Christie served as a voluntary nurse during World War I.

As such, she soon developed an interest in the medicines of the day -- exotically named substances which in strong doses could be lethal.

Strychnine, morphine, cyanide -- "people could access them frighteningly easily," said Harkup.

"You could go to a chemist and just buy arsenic or cyanide and no one would ask any questions. Quite worrying."

Ever since her first book in 1920, "The Mysterious Affair at Styles", Christie used poison.

The victim in that case was Mrs Inglethorp and the toxic substance deployed was strychnine, which was often used as a stimulant to give old ladies a little pick-me-up but in higher doses paralyses the muscles.

"It's a very unpleasant way to die," said Ali Marshall, head gardener at Torre Abbey, a historic building in Torquay.

In the grounds of this almost 900-year-old abbey, Marshall has planted a small flowerbed featuring some of the plants from which Christie's favourite poisons derive.

"She's named queen of crime but she should be queen of poison," said Marshall, noting that more than half of Christie's victims suffered this fate.  

- 'Death takes several days' -One of the author's favourite poisons, cyanide, is present in bitter almonds.

"It's a great poison: very fast, very quick acting and you don't need much," said Marshall.

There was also digitalis, derived from foxgloves, which was used to treat heart conditions.

"Several of her characters took digitalis; you just have to give them a bit more," the gardener added.

And of course there was arsenic, which was used to get rid of rats, but also to knock off a sour-tempered aunt or a father who wouldn't let go of the purse strings.

"One of my favourites is the castor oil plant which gives ricin. Death takes several days, so you have plenty of time to fly to Australia," joked Marshall.

Christie obtained her chemist's diploma in 1917 under the supervision of a teacher with the unfortunate habit of making errors of dosage and walking around with a vial of poison in his pocket to make himself feel powerful.

As an author, Christie became so meticulous in her description of doses and the action of these poisons that she was once accused of providing the perfect handbook for apprentice poisoners.

On the other hand, she carefully avoided describing their most unpleasant consequences, like vomiting and diarrhoea. In her books, victims die cleanly, even when it involves cracking their skull.

Poison is often administered in an appetising dish, described beforehand in such a way as to leave the reader salivating.

"Victims are poisoned with cakes, sandwiches, tea. Champagne too is very dangerous," said Anne Martinetti, who has made an inventory of all the novelist's deadly recipes in the cookbook "Cremes et Chatiments", or "Creams and Punishments".




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