Natalie Haynes: And all the adaptations lived happily ever after...

The thing is...

The thing is that if you want your literary classics to be perfect and unadulterated, you should get them off your pristine bookshelves, never open the spine more than a tiny bit, and make sure you have a nice bookmark. No corner-creasing as you cram it back in your bag and leap off a train, or the ghost of books-yet-to-come will haunt you when the bell tolls one.

And what you especially shouldn't do is watch any adaptation of them at all, in any medium. By definition, an adaptation involves changing the thing it's based on. And if you believe that Dickens, Trollope or whoever is completely perfect as he is, you can't fail to be disappointed by the choices a writer or director makes when adapting it. This is, however, an asinine attitude to have towards a TV show if you actually intend to watch it.

When the BBC revealed that it had taken liberties with the ending of its new Great Expectations adaptation, which airs on 27 December, it was accused of every kind of philistinism. Bad enough that it had cast the altogether minxy Gillian Anderson (of X-Files fame) to play Miss Havisham, even though she's only 43. Purists couldn't have been more shocked if the BBC'd cast ET to play Magwitch.

But the prospect of a new ending is even worse, it seems, in spite of the fact that Dickens himself wrote two endings, so presumably felt rather less reverential about his work than his most swivel-eyed fans do. Robert Douglas-Fairhurst, the historical adviser to the BBC for its new version, has no problem with the changes: "I think Dickens is strong enough to withstand anything we do to him. He has a chameleon-like ability to adapt to changing circumstances."

And that, of course, is the truth of the matter. Dickens, like Austen, wrote wonderful stories which work pretty much whatever you chuck at them. You can adapt them to be as close to the original as possible, or you can transport them to a contemporary setting, and they will work beautifully either way. Clueless is at least as good a film as the Gwyneth Paltrow version of Emma, and the fact that Miss Wodehouse is in an empire-line frock while Cher strides through a shopping mall in a mini-skirt is neither here nor there.

A Christmas Carol has been adapted dozens of times and never better than by the Muppets. Surely if a story can withstand Bob and Mrs Cratchit being played by a frog and a pig, it can withstand anything. So let's raise our expectations and stop being such scrooges.