Dr Johnson. Samuel Johnson. What can you tell me about him? Come on, come on, I'll have to hurry you. “When a man is tired of London, he is tired of life.” Yes, very good. Anyone else? Perhaps those of you who saw the telly adaptation of Vanity Fair remember the scene in which Becky Sharp, departing Miss Pinkerton's academy for young ladies on Chiswick Mall with her friend, Miss Amelia Sedley, hurls from the window of her carriage the copy of Johnson's dictionary with which she has just been presented by Miss Jemima Pinkerton.

While we're searching the scrap-basket of memory, the ailurophiles among us will doubtless recall the bit in Boswell's Life of Samuel Johnson where Bozzy admires Johnson's cat, Hodge, and Johnson tactlessly replies “Why yes, Sir, but I have had cats whom I liked better than this,” and then “as if perceiving Hodge to be out of countenance, [adds] ‘but he is a very fine cat, a very fine cat indeed'.”

A well-worn aphorism, an act of literary defiance and a moment of endearing anthropomorphism - is this really all that remains in the popular consciousness of one of the towering figures of English literature, as great as Shakespeare, Chaucer or Dickens and far better documented, certainly than the first two and arguably better even than Dickens, thanks to the close surveillance of his intimate friend and biographer, Boswell.

According to Johnson's latest biographer, Peter Martin, not even those thin shreds of Johnson's reputation may now survive. In the preface to his new biography, to be published on August 7, he writes that “I have been surprised from spot interviews in the high streets of several English towns that only about a quarter of the people I spoke to could identify him. Some wondered whether he was a boxer, or a contemporary of Shakespeare's, or a Canadian sprinter convicted of drugtaking, or a leading Conservative MP ... the problem is partly that few people read Johnson today...”

Then again, if you're counting heads, few people today - other than students of English literature - actually read Chaucer, Shakespeare, Fielding, Browning or Eliot. There is a whole literary canon of dead, white males languishing largely unread, with only a sort of honorific obeisance to their names to keep their reputations warm. But with so much excellent contemporary writing around, need it really bother us if only one high street shopper in four can tell the difference between Samuel and Boris Johnson?

Peter Martin evidently thinks it should, to the extent that, a year before the tercentenary of Johnson's birth in September 1709, he has published a substantial biography: “The first,” say his publishers, “for over 30 years”. The biography comes garlanded with praise by such authorities as Harold Bloom, who called it “a profoundly poignant and eloquent account of the Western world's greatest literary critic”. But there are dissenting voices: already it has been elegantly savaged by a critic who found it coarsely written, inaccurate and amateurish - a feeble effort by comparison with the magnificent Walter Jackson Bate biography of 1977 (now sadly out of print).

All of which may well be true. On a swift reading of the Martin I remarked a certain jauntiness of tone that seems almost wilfully pitched so as to upset fastidious Johnsonians. Then again, the book is a fast, palatable read and even if it does leave out the most touching passages of Johnson's last letter to his friend Mrs Thrale, and misquotes with a cacophonous tin ear from The Vanity of Human Wishes, perhaps this need not matter so very much. Johnson himself, after all, was cheerfully insouciant about certain errors in his dictionary. And the Martin biography, if it is read, will do him at least the service of reminding us what kind of a man Sam Johnson was.

I studied him in my teens and loved him then (not such an odd infatuation as it may seem - Johnson was fond of, and very kind to, bookish young women). I thought I knew him well and was amazed to find how much I had forgotten. I remembered Johnson poor, neglected, melancholy and wrestling, agonised, with his own human failing in the face of death, but had forgotten Johnson raffish, clubbable, domestic, delighted and delightful. Beryl Bainbridge's wonderful novel According to Queeney conjures a lovely, unexpected image of Johnson in private, dwelling at the heart of his adopted family, the Thrales of Streatham, but even that neglects his great funniness.

“I never knew a man laugh more heartily,” wrote Boswell. “He laughs like a rhinoceros,” said his friend, the bookseller Thomas Davies. Fanny Burney recorded in her diary Johnson laughing so hard at a conversation she was having with Mrs Thrale that the chair shook under him. Another friend, Bennet Langton, remembered him taking a sudden notion to roll down a hill in Lincolnshire. Langton tried to discourage the preposterous idea, but Johnson persisted, saying that he “had not had a roll for a long time”. Emptying his pockets, he lay down and “descended, turning himself over and over till he came to the bottom”.

And there, with the image of the Great Cham rolling down a Lincolnshire hillside, I must leave you, for this is my last column in this space. For the past decade I have had the great privilege of being read, and responded to, by the most intelligent of readers. Your letters have amused, instructed and occasionally reproved me. I have been grateful for them all. So, thank you. And farewell.

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