LIKE Robert Maxwell, Robert the Bruce and Robert Geldof, Robert Llewellyn is a man who arouses strong feelings. Women generally find him charming and perceptive and wish their partners were like him, men tend to find him nauseating and think chemical castration would be too good for him. When asked what they really think of him, however, most people reply: 'Who is he?'

This is unfortunate, as his new book The Reconstructed Heart (Simon & Schuster) goes a long way towards solving some of the major psychological puzzles of our times - including why men are the way they are, why they keep going on about it all the time, and why they blame everything that goes wrong in their lives on women.

The book, he explained to me this week, is the product of 20 years research in libraries, during nude psychodrama marathons, and on genital balancing weekends. Apart from valuable reference sources like Christopher Dickins' What on Earth are Ladies Going on About?, Frances Milson's Gender and Misery, and the Bertrand Bluvier film Lovely Long Dresses, Llewellyn says he also drew heavily on Speffendaffer and Tolleringham's seminal pop psychology guide, How To Find Out What People Want To Read About Themselves. Some of the findings he comes up with may seem a little suspect: his claim, for instance, that magazine articles about New Man always have a question-mark after their title, or his description of non-sexist man as being on a par with non-violent assault rifle.

Nevertheless, he manages to construct a theory which is of use to all men trying to grapple with feminism. He explains, for example, that there are two types of people - men and women. And he talks to John Blake - a low- achieving bank clerk who 'has an unfortunate tendency to stand too near people he doesn't know and smile at them' - about the time he killed several women and children with his car. It was the council's fault, Blake says, for putting the bus stop in a stupid place. He also discusses emotional maturity with a man called Barry Tenderton. Asked if he has ever sulked, Tenderton reacts by 'pouting, folding his arms, and looking out of the window'. He later admits that, when his wife has a go at him, 'I sit in the corner and look at the ground for about a month. That shows her.'

The main thesis of Llewellyn's book is that men like John Blake and Barry Tenderton are what psychosexual consultants correctly term normal - and that other men fall into three distinct categories: defensive types who say 'it's not fair' a lot, are 'prone to crass attempts at deception' and have 'passionately held beliefs that change at a moment's notice'; self-loathing types who say 'as a man' a lot, 'strive to outdo women in criticism of their own gender' and in previous eras were nearly always vicars; and reconstructed types who 'do the housework, are great in bed and don't get iffy when you mention words like love and commitment'. The author informs us he has been normal in the past but is now completely reconstructed.

His interest in categorising men began when a Germaine Greer lookalike at school labelled him a 'sexist git'. He identifies the early Seventies as the moment when it dawned on some of his peers that 'just possibly men hadn't always been right about absolutely everything'. He noticed that those who realised this felt guilty and miserable, talked about it a lot, wrote the odd poem but otherwise carried on much as before. Domestic tasks continued to elude them. 'I kept meeting men who thought I was gay because I'd made a cake,' he remembers. 'They hadn't realised it wasn't that hard - especially compared to things they would do, like climb under a car and bash their heads on pieces of oily metal.' The book started out as a lecture which has been given throughout the world and on Channel 4 television. A follow-up is already in progress. Called From Volvo to Vulva (The Male Journey to Understanding Women), it has had a successful tryout at London's Bloomsbury Theatre and offers scientific data which confirms what many have suspected all along: that men's health deteriorates if they don't sit down and read newspapers a lot - especially when there is any vacuuming to be done.

Like everyone with something new and important to say, Llewellyn has inevitably run into critical flak. Some suggest he isn't a psychosexual consultant at all, and only wrote the book to get off with feminists at lectures, book signings and seminars. He defends himself by mentioning a relationship he is in right now which makes him unavailable 'for any low-impact sexual dalliance'. It was with great reluctance that he gave me his mobile telephone number or allowed it to be printed in his book. It's 0800 8332 199190 and you can reverse the charges.

Others dismiss his work as a send-up. They accuse him of fabricating interviews and using humour to reveal truths about men while making fun of the po-faced, breast-beating individuals who usually attempt to do so. When I put this to Llewellyn, he smiled, waved one hand in the air and compared the mentality of those who say this with a cynic he interviewed for the book - a man who claimed the only way men have changed in the last 20 years is 'to get better at lying'. Hand on heart and staring straight into my eyes, he swore everything in The Unreconstructed Heart is true. Read it and believe.