After a brief period of reflection, Stevenson wrote it all out again, 'in another three days of feverish industry'.

The legend put about by RLS's stepson Lloyd Osbourne has it that he wrote a draft in three days, after being awakened from a dream, then threw it into the fire when his wife Fanny, Lloyd's mother, complained that he had 'missed the allegory'. It was Stevenson's response to a request from the publisher Charles Longman for a ghost story for the Christmas number of Longman's Magazine, in which he gave readers a taste of his best authors. 'Strange Case of Dr Jekyll and Mr Hyde' (the definite article is missing from the original title) was written in about six weeks in the autumn of 1885.

Stevenson's respectable physician Henry Jekyll appears to have had a similar desire, though his appeal was not to the deity but the pharmaceutical cabinet, with disastrous results. The poet Hugo Williams has compressed the essence into a single line - 'God give me strength to lead a double life' - a plea to be in two places at once, not necessarily legitimately, without the inconvenience of a guilty conscience. 'Dr Jekyll and Mr Hyde' belongs to everyone who has ever referred to themselves in the third person, or cursed their own 'split personality', or praised their 'better nature'. Between 19, Japanese publishers offered readers seven translations to choose from, including one in graphic-novel form. Five separate editions of the book were issued in France in 1947, not long after the end of a different horror story. There are various pornographic adaptations, including Dr Sexual and Mr Hyde. In 1925, Stan Laurel starred in Dr Pyckle and Mr Pryde, which competed with When Quackel Did Hyde of 1920. Back in the human zone, there have been Abbott and Costello and Jerry Lewis versions of Stevenson's novella. There is a Daffy Duck Jekyll and Hyde, and Bugs Bunny also makes use of it. The same storyline drives another cartoon of the 1940s, 'Mighty Mouse Meets Jekyll and Hyde Cat', though this time it is the cat who mixes a cocktail in the doctor's laboratory, changing from cute puss into a beast with fangs and fiendish claws. The pair exit with Jerry in pursuit, wielding a swatter. At the end of 'Dr Jekyll and Mr Mouse', Tom tries lapping up the milk - only to be reduced to the size of a fly.

After a few sips, Jerry swells into supermouse, terrorising Tom, who normally holds the upper paw. Here, a saucer of milk spiked with moth balls and bug powder is enough to transform an ordinary, decent soul - the mouse - into a monster. A mong the many screen adaptations of Robert Louis Stevenson's novella 'Strange Case of Dr Jekyll and Mr Hyde' is a seven-minute Tom and Jerry film made by Hanna-Barbera in 1947.

Robert louis stevenson jekyll and hyde