How often have you sat through a Shakespeare play or read a text, feeling that you're missing something? He may be England's greatest playwright and his phrases may litter our everyday language, but he's not easy and (let's whisper it) can often seem a bit dull. All that impenetrable language!

Reading Pauline Kiernan's book, Filthy Shakespeare: Shakespeare's Most Outrageous Sexual Puns, may well reverse such attitudes, and surprise those whose view of Shakespeare comes from bowdlerised texts.

Explaining how and why he used outrageous sexual puns throughout his works, she brings the Bard and his plays alive in the most extraordinary way, in the process rescuing him from the aspic of his elevated reputation. The book is likely to thoroughly shock a lot of people, particularly with its assertion that Shakespeare's women were as filthy as the men and that sexual punning was not confined to the lower orders.

She begins with a fascinating and lengthy introduction about sexuality in Shakespeare's time. This is followed by more than 70 extracts from his plays and sonnets, under headings like 'cuckold', 'brothels', 'impotence' and 'female whore', where she explains the puns and what he was trying to say to his audiences.

Every page breathes her love of Shakespeare and her wish to communicate the man's genius and his brilliant understanding of the human condition. She does it extremely well; combining her breadth of knowledge as an Oxford University-educated Shakespearean scholar with her skills as a former journalist and award-winning playwright to provide a thought-provoking, captivating book.

Some readers may be put off by the explicit language, but - as she pointed out when we met at her home in Charlbury - Shakespeare used it as well. There were many more words in use than today and for a long time we lost the meanings.

"I'm not putting words into his mouth, the sexual puns are there to be interpreted," she said. "My whole approach hasn't been to cobble together some smutty extracts from Shakespeare. I have a very serious agenda and it's to demonstrate that when Shakespeare tackled really big issues like war, morality, poverty, philosophy, he very often used sexual puns to do so."

Now 55, Pauline has been interested in Shakespeare since she was five, when her sister introduced her "to the strange, wondrous-sounding language of a ham omelette mysteriously troubled by a bee". Seeing David Warner as Hamlet in a Peter Hall production seduced her completely.

After ten years working as a journalist, she did an English degree and then a doctorate on Shakespeare at University College, Oxford. She also spent five years as the Leverhulme Research Fellow at Shakespeare's Globe Theatre in London when it first opened.

I asked if working there had helped her understand the plays better.

"Yes, it did," she said. "The relationship with the audience is so completely different. It's in daylight. There's no special lighting, or props, or set design, and it makes you realise more than ever - something I knew in theory, but in practice, I was able to discover - that listening is absolutely the main thing you have to do in the theatre. It's not what you see, it's what you hear."

She uses extracts from the plays to show us what Shakespeare was trying to say, such as what he thought about women's place in society (various), what it meant to be a man (in particular in Macbeth), and the morality of war (Henry V).

"Everybody says we can never know what Shakespeare thought about something, which I find absolutely extraordinary," Pauline said. "It's quite obvious what he thinks."

She uses an example of a speech in Henry V, where he is explaining to the governor of Harfleur what his soldiers will do to the women of the town if he does not surrender. "It's a speech of absolute filth and violence against women. Shakespeare's obsessed with this idea that in wartime it's okay to rape. He's revulsed by it." The speech shows exactly what he thought about things like this, she says.

I asked what she'd enjoyed about writing the book.

"I've enjoyed it all," she said. "Shakespeare is probably the world's most famous playwright, but relatively few people like him or understand him or can be bothered to read his plays. I would love to find a way to get people who are completely turned off him to get turned on him."

After reading the book, I certainly was, but don't go reading any double meanings into that.

Filthy Shakespeare: Shakespeare's Most Outrageous Sexual Puns is published by Quercus at £12.99.