While we may not know their names, anonymous writers have long shaped our worldview, says Brooke Magnanti, who wrote as sex blogger Belle de Jour.

How do we know who's written the words we love to read?

The obvious answer is by the name on the cover. But the tradition of anonymity subverts any easy answers.

As someone who spent six years writing under a pen name, the topic of anonymity is fascinating to me. When I started blogging as Belle de Jour it was for practical self-protection - I didn't want to risk my career in science by people knowing I was also a call girl.

There are all kinds of reasons for wanting to be anonymous, and they started thousands of years before humankind even imagined blogs and the internet.

From the earliest times, we have told stories and tales, histories and thoughts. But even though sharing our experience of the world is a human universal, wanting to be recognised for that isn't.

Belle de Jour Brooke Magnanti wrote under this nom de plume about working for an escort agency to earn money to study for a PhD

Her pseudonym means "beauty of the day" and alludes to 1928 novel and 1967 film of the same name

Magnanti revealed her identity in the Sunday Times in November 2009, saying: "I don't want this massive secret over me any more."

She is now a research scientist, writer and blogger

In an interview in October 2012 Magnanti called for prostitution to be decriminalised

At many times in history, being known for what you write has carried a high price. Laws from imperial Rome to 17th Century England made it possible for rulers to execute those who criticised them and their actions.

Harsh laws are in place even today, as those tweeting and blogging during the various Arab Spring uprisings can attest. Anonymity can save your life.

Literature mavens tease out real lives from the mischievous games authors have used to hide themselves. While we are well acquainted with the Bronte sisters today, they originally published under the names Currer, Ellis and Acton Bell.

Jonathan Swift got someone else to write out his manuscripts so his handwriting wouldn't be recognised by the printer. Swift saw it as part of the fun to keep people guessing.

"If there's one thing the history of literary anonymity teaches you, it's that very often anonymity has nothing to do with wanting to stay hidden," says John Mullan, professor of English at University College London.

Anonymity is a useful tool for people whose lives are outside the mainstream. Letting go of your name frees you to tell a truth that many people never see, or try desperately to ignore. It gives certain things more weight, a kind of everywhere-and-nowhere sense where the reader feels they might even be reading the inner thoughts of someone they know. It's a powerful tool.

Find out more Belle de Jour's History Of Anon will be broadcast on BBC Radio 4, Monday 31 December to Friday 4 January at 13:45 GMT Or catch up later on iPlayer

In the internet age, we have become increasingly concerned about the effects of anonymous online commentary. Anonymous bloggers can have enormous global audiences. "Trolls" can bring criticism straight to the computer screens of the people they disagree with. These trends are solidly in the tradition of literary anonymity - from unsigned political tracts to biting satirical graffiti, we've seen it all before.

In the UK today anonymity still has a place, and being unmasked is one risk of going anonymous. Policeman Richard Horton found his email had been hacked when the Times exposed him as the author of the blog Nightjack.

The News International newspaper named him in 2009 after the High Court refused to grant him anonymity. Horton was issued a warning by his employers Lancashire Constabulary after his award-winning blog exposed the realities of modern-day policing.

He sued the paper in October 2012 and was paid £42,500 ($68,000).

Mr President, I saw it as a tribute to a larger-than-life politician Joe Klein to Bill Clinton when asked why he wrote Primary Colors

Joe Klein, formerly anonymous author of Primary Colors, the 2002 novel about a US President caught in a sex scandal, suffered a backlash from fellow journalists for denying, and then having to admit, he'd written the book.

Many had guessed that Klein was the author but he repeatedly denied it - and even staked his journalistic credibility on his denial in an interview.

I went to great lengths to remain anonymous, including complicated contracts involving a shell company held in other people's names, encrypted email and more. But in the end it is always about relationships rather than technology. A writer who lets the secret slip to the wrong person will find the precautions simply don't matter.

So what did I learn? Well, first of all, the effects of anonymity are more important for the anonymous writer than they are for the audience. We'd still be dotty over Jane Austen's books if, like her contemporary audience, we never knew her name.

The writing has enough authority and detail to carry us along in her inner world. Knowing her name, where she lived, and seeing the piecrust table where she painstakingly wrote out her manuscripts is interesting, but it's trivia. It's not what makes her novels sing.

Image caption Billie Piper played the character of Belle de Jour in the television series

Losing anonymity, if you're alive when it happens, can be a double-edged sword for a writer. The risks a writer took when they chose anonymity don't go away when they're named. But it does expose them to the people who gave their words an audience.

I went to great lengths to remain anonymous, including complicated contracts involving a shell company held in other people's names, encrypted email and more

In my own experience, this has meant not only can I connect with like-minded folks, but I'm now also able to answer those critics who sneered I couldn't possibly be real. That hasn't put them off continuing to criticise, of course, but it's great fun finally to be able to answer back.

And in the end, it turns out Anonymous is one of our greatest writers.

"From the medieval period to the modern period there have been authors who have enjoyed playing with and experimenting with anonymity, and it never really goes out of fashion," says Marcy North, author of The Anonymous Renaissance: Cultures of Discretion in Tudor-Stuart England.

Anon was, as Virginia Woolf noted in one of her final unpublished essays, "the voice that broke the silence of the forest". Elsewhere she suggested that "Anonymous was a woman". For anonymity has definitely been widely used by women throughout the ages, whether they're writing about relationships, sex or anything else.

Without Anonymous, there are so many classics we would not have had - Gawain and the Green Knight, virtually all of the Bible and other religious texts.

Anon is allowed a greater creative freedom than a named writer is, greater political influence than a common man can ever attain, and far more longevity than we would guess.

Obviously, I'm a great fan of Anon's work, but then, as a formerly anonymous author, I would say that, wouldn't I?

Belle de Jour's History Of Anon will be broadcast on BBC Radio 4, Monday 31 December to Friday 4 January at 13:45 GMT

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