Rarely seen or heard celebrity ghost writers almost never get their chance to reveal their secrets and experiences of sitting with some of this country’s best known stars.

Often gagged by contractual agreements – which could even include a clause forbidding them from attending the book’s launch party – some may assume that celebs actually pen their own memoirs.

Mark McCrum has forged a career out of sitting down with the likes of singer Robbie Williams and award-winning documentarian Bruce Parry for days, maybe months, to put together a book detailing their life.

If it sounds easy, think again. Often the pair may have been put in the room by the star’s management.

The celebrity in question may not want to even be there, let alone reveal the darkest periods of their rise and fall, to a person they have just met.

Ghost writers, as the 55-year-old explains, are often shunned by fellow authors, too.

“I think other authors think you are very low on the food chain.

“Booker Prize winners are at the top, then chick lit authors, then us,” says the Highgate resident of 25 years. “We are probably the seventh circle of hell.”

In 2001, McCrum spent two and a half months with Take That idol Robbie Williams, after being allowed unprecedented access for his European tour by his management.

Despite being given a backstage pass – one of only three to be given out – McCrum ran into difficulties trying to win over the notoriously complex pop star.

“I spent about six weeks on the road and then I hung around with him for a month afterwards – but it was fun.

“I was one of three people allowed into a dressing room. We kind of broke the [story about the] introspective, self-doubting side of Robbie Williams.”

Jade Goody

McCrum will appear with Shannon Kyle, another esteemed ghost writer, at the literary festival.

Kyle has written the ‘autobiographies’ of Jade Goody, Katie Piper and Emma O’Reilly, better known as Lance Armstrong’s former masseuse.

McCrum says he and Kyle do not often get this chance to give such a talk and will often only meet up once a year at Halloween, when literary agent Andrew Lownie hosts a party especially for ghost writers.

When pressed, McCrum refuses to reveal many details of the annual get-together, but he does admit plenty of industry secrets are told.

“Secrets are shared,” he says. “I enjoy telling Shannon stuff, but it will never go beyond that – we are quite discreet as a group.”

Mark McCrum and Shannon Kyle will be discussing how to write in someone else’s voice on Monday, September 15 at 2pm. Tickets cost £8.