The Fifty Shades of Grey effect is leaving Norwich tickled (or possibly lightly spanked) pink as book buyers queue up to read for themselves the erotic tale that everyone's talking about.

Written by London TV executive EL James, the book was developed from stories posted on fan fiction websites for the Twilight saga, a series of five fantasy films based on the Twilight series novels by author Stephenie Meyer.

Adapted and rewritten, the original posts were split into three parts: Fifty Shades of Grey, Fifty Shades Darker and Fifty Shades Freed, the first of which was released as an e-book in May 2011.

Sales grew steadily through word of mouth as readers discovered what was quickly dubbed 'mummy porn': the story of a young college student, Anastasia Steele, who becomes involved with the hugely rich Christian Grey who has, as Wikipedia delicately puts it, 'a singular erotic taste' (or, as my Nan would have put it, 'isn't quite right in the top storey').

Catapaulted to the top of the best-sellers list through word-of-mouth, the book has been flying off shelves thanks to its mildly racy bondage encounters (although be warned: it takes 85 pages for Christian to deflower Anastasia during which she constantly refers to her 'inner goddess' so often that it's astonishing he maintains any interest in her whatsoever).

Christian has a bondage playroom in his mansion and makes Anastasia sign a contract about what she is, and isn't, willing to do as his sexual submissive: it's like Mills and Boon on ecstasy or the erotic novel Charles Dickens might have written, Oliver Twisted.

For those that don't harbour a secret desire to be lightly swatted, blindfolded, trussed up, treated like a halfwit or stalked, solace can be taken in other, less shady corners: Christian buys Ana a brand new sports car. That's a pretty sexy scene.

In Norwich, Fifty Shades of Grey has proven popular with book buyers, who have readily embraced EL James' forbidden, dark romance.

Mike Butler, buyer/manager of Jarrolds' book department, said the novel was being bought by women of all ages and that many customers were saying it had been recommended to them by a friend or relative.

'This is the fastest selling paperback book ever and the publicity surrounding it has been huge, which means it keeps on selling,' he said.

'We're now seeing all kinds of publishers putting out copycat books. For some reason, Fifty Shades of Grey has really captured people's imaginations.

'People are coming in and buying the box set of three titles, buying it as a gift or for themselves, and why not? It's a brilliant piece of escapism.'

One such avid reader is Sam Skouros, 31, who works in TopMan and has sped through two of the three books and is currently reading the third.

'Lots of the girls at the shop were talking about the book but I'm the kind of person that doesn't like to do something just because someone else is doing it, so I didn't immediately rush out and buy it,' she said.

'Eventually, though, I just couldn't resist. A friend bought it at the same time and we said we'd compare notes on it. I didn't think I'd like it because I usually read biographies and historical books, not this kind of thing.

'To be honest, I was a bit disappointed that it was quite tame – I didn't find it that naughty at all. I couldn't help myself getting interested in Ana and Christian's story, though, and the other books are a bit more adventurous.

'When I went to buy the first book, there were a few women looking at the same section and we were all chatting about it. For me, the books aren't about the sex they're about finding out what's going to happen between the two characters.

'It's not great literature by any means and Christian Grey doesn't really do it for me, although talking to other girls about it a lot of them say 'I need a Christian in my life' because he's rich, handsome and the more you get into the books, the more you realise that he does have a vulnerable side.

'That's what every woman wants – to be the one who sees a man's vulnerability,' she explained.

And it's not just book sellers who are feeling warm inside thanks to Fifty Shades of Grey.

Martin Price, owner of Sinsins Love Store in Charing Cross, has noticed an uptake in sales of bondage items and, ahem, marital aids, since the popularity of the book.

'It's almost given people permission to explore their sexuality which is great.

'They may have felt that they'd be judged for wanting to do something a bit different, but with everyone talking about the book, they feel more comfortable,' he said.

'In our shop, we've moved away from the novelty items and towards a far more boutique feel which means that when people come in, they can look around in a shop that doesn't feel sleazy or grubby.

'Personally, I don't see why people can't come into the shop and treat their purchases in the same way that they'd buy a handbag or a bottle of perfume. Sex should be part of people's normal conversations, not something to worry about or be ashamed of.

'We've had women coming in after reading the book and we've had men coming in who say their partner has read the book,' he explained.

'Women are the ones who want to know how things work whereas most blokes just come in, buy and leave.

'Women seem to be more creative and more intellectual about their sexual choices. If Fifty Shades of Grey has helped more women think about sex, then it can only be a good thing.'

Personally, I've found B&Q paint charts more erotic than Fifty Shades of Grey, but then perhaps it's because I haven't discovered my inner goddess.

And even if I had, I think my inner goddess would have something to say about a man who prepares for an encounter by saying: 'Ready for some contraception?'

I can feel a headache coming on.

My (very hidden) inner goddess thanks Jarrolds for giving me a copy of Fifty Shades of Grey. Fear not, I won't be back trying to blag the sequels.

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