Anything can happen when the lives of real people are filmed. An image becomes fixed, the celluloid version often transcending the reality, against all reason. The same applies to screen versions of classic works: and the younger you are when you first see them, the harder it is to shake them off, as they are lodged in childhood memories. Thanks to the BBC’s classic serials of the 1950s, which were outstandingly well cast, the definitive Mr Darcy, for me, will always be Alan Badel: that patrician profile with the built-in sneer seemed wonderfully right. My Mr Rochester remains Stanley Baker; my David Copperfield is Robert Hardy. When they televised Shakespeare’s history plays in 1961, Sean Connery became my Harry Hotspur (before he turned into my only acceptable James Bond), and the late Paul Daneman was my ideal Richard III, even after I saw the famous Olivier film. Such performances have an adhesive tenacity. Having seen every production of John Mortimer’s A Voyage Round My Father, in which the theatrical knights Guinness, Redgrave, Olivier and Jacobi have all since given splendid renditions of Clifford Mortimer, the one I can never forget was by the late, un-knighted Mark Dignam, who was quite perfect in the original version in 1969.

On the big screen, not all biopics have this ineradicable sticking power. But General Patton must have been exactly like George C. Scott, Butch and Sundance are Newman and Redford, Buddy Holly is the otherwise forgotten Gary Busey, Ike and Tina Turner are Laurence Fishburne and Angela Bassett, Dorothy Parker is Jennifer Jason Leigh, Isadora Duncan is Vanessa Redgrave, Joe Orton is Gary Oldman, Muhammad Ali is Will Smith and Johnny Cash’s wife June is forever Reese Witherspoon.

Now it’s Beatrix Potter’s turn. Nobody can be unaware, this week, of Potter’s life: Linda Lear’s new biography is being serialised on Radio 4; a feature on Christmas Eve examined her scientific pre-eminence as a natural historian; and of course, the film Miss Potter is released on January 5. As from next week, the little round figure from Delmar Banner’s 1938 painting of Beatrix in the National Portrait Gallery will be superseded, as an image, by the sweet-faced Texan Renée Zellweger wearing the dowdy costumes she correctly insisted on. In the same way, the popular image of Elizabeth Barrett Browning became, in 1934, Norma Shearer on a chaise-longue, with Charles Laughton embodying the fierce father.

For a biographer who has studied the minutiae of a life for years it can be irksome. A biographer pursues truth, a film director seeks drama. One of Potter’s earlier biographers, Judy Taylor, alerted me to the licence the new film takes with the facts, such as a Christmas party scene at the Potters’ house. They were strict Unitarians and did not observe Christmas. Does this matter? In film terms, perhaps not.

Feature films are not documentaries. They telescope and romanticise events. Moreover, films about writers can never show the creative process: only a writer who is also a talker and/or has a life of dramatic conflict, such as Oscar Wilde, can satisfy cinematic demands. But for anyone who cares about facts, biographies outclass any film.

For instance, the biography shows, as the film cannot, how Beatrix Potter taught herself to be a meticulous anatomist of animals. Rabbits, bats, reptiles, snakes, hedgehogs, mice and snails were collected, brought home, drawn and painted; when they died they were boiled and skinned, their skeletons studied and labelled. The original rabbit named Peter was bought for 4s 6d at a pet-shop in Shepherds Bush. Potter took him everywhere, taught him to do tricks, and wrote, when he died at the age of 9: “His disposition was uniformly amiable and his temper unfailingly sweet. An affectionate companion and a quiet friend.” A film gives the broad sweep; but accumulated detail is what makes a biography. Such as the fact that Potter’s tales began as illustrated letters to the children of her former governess (“My dear Noel, I don’t know what to write to you, so I shall tell you a story . . .”) Or that Frederick Warne & Co followed Potter’s strict rules about format — “small enough for little hands to hold” — typography, relationship of text to illustration, and price: so they sold the books at below cost price for decades, to keep them within a child’s spending power. No wonder Warne went down the drain.

Film-makers can’t resist their embellishments. The Queen never drove alone in her Land Rover to gaze on a dead stag, but it made a moving scene. In Peter Morgan’s Channel 4 film Longford, he originally had a scene showing the family being served by white-gloved butlers — until Longford’s biographer intervened to point out that the Longfords at home were never so grand. Morgan still inserted a fanciful episode in which Elizabeth Longford sneaked off to the Public Record Office to do her own research on Myra Hindley. It never happened. Nor did the missionary Gladys Aylward have an affair with a Chinese officer, as Ingrid Bergman did in The Inn of the Sixth Happiness. Films devour interesting lives. But art cannot always imitate life.

I failed the Scrooge test - but only just

Hunter Davies, who writes a column called Mean With Money in The Sunday Times, prides himself on being North London’s Scrooge when it comes to Christmas giving. The most anyone in his family is allowed to spend on a present is £10. This is a severe test of ingenuity. I tried it for just one day last week, and it went like this: Teddyfur bootslippers, £12.99; Italian panettone, £12.99; Oral B electric toothbrush, £12.99; leggings, £12.99; umbrella, £12.99; swimming goggles, £12.99. Finally I went into our local bookshop. “Amo, Amas, Amat . . . and all that,” I said. “Huh?” said the assistant. “The Latin book by Harry Mount.” He found a copy. Eyeing its small size, I said hopefully, “£10 ?” “No, £12.99,” he said. Perhaps £12.99 is the new tenner. Even so, the Grove young were not thrilled.

Mangled Minglish

Oliver A. Wang, Tammy Xiong, Deloris Floyd, Worms Firewalls, Jolene Mohr, Gobnata Burnside, Sabrina Hooker, Humberto McPhee: just a few of the preposterous names clogging up my e-mail inbox this week with mangled messages about penis extensions, Viagra etc. They are, I’ve decided, the same people who translate menus and notices in hotels into hilarious Minglish. Those mangled warnings, instructions and menus are collected in Charlie Croker’s Lost in Translation, and included in John Julius Norwich’s annual round robin, Christmas Crackers. “Measles not included in room charge”; “If you telephone for room service you will get the answer you deserve”; “Chopped cow with a wire through it”; “Our wines leave you nothing to hope for”. More fun to read at the table than actual Christmas cracker jokes.

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