It would be nice to report that Holroyd has now combined his two books and added some new material in order to help reverse this decline but the additions are not very important and the exercise seems to have been more a question of fiddling with the writing - the author burnishing his own image rather than that of his subject. The cover says it all: Holroyd's name is in larger print than John's, an acknowledgement by the publisher that the biographer is better-known than the artist and to make sure we get the point there is now a long preface outlining his labours: the subtle skills needed to handle surviving relatives, the titillating fact that Holroyd likes to write in bed.
All this takes up more space than is devoted to explaining the paintings. Indeed we are told so little about John's work in the first half of the book that it is difficult to see why he was accepted as a genius by so many of his contemporaries even while he was at the Slade. We are told that his drawings were marvellous, if a little old fashioned, which makes it even harder to imagine what Virginia Woolf meant when she referred to the period as "the age of Augustus John" and even harder still to see why so many older artists considered him a dangerous poseur.
Holroyd tries to sidestep such criticism by asserting in his preface that his is a biography and not an art book, as if the inner world of an artist's work can be divorced from his everyday doings. There are certainly some advantages in this approach as it leaves him free to concentrate on the period and the milieu that John inhabited and prompts an unforgettable reconstruction of the narrow London art-world at the turn of the century, with the New England Art Club, of which John was a leading light, holding a meeting in 1904 to quibble over whether Lucien Pissarro, a foreigner, could be admitted to membership - and this at a time when the young artists of the world were gathering in Paris to launch the modern movement in painting. Holroyd is at his best when deftly sketching in minor characters like the Hon. Mrs Dowdall who shocked Liverpool society by walking barefoot in the mud and whose awful jokes were said to have emptied the drawing rooms of Edwardian England.
But such concision is absent when it comes to the main thrust of the book, much of which is given over to accounts of John's irregular family life - the notorious menage-a- trois, the idly conceived children scattered everywhere so that even Dorelia found it hard to say with certainty which belonged to whom. Not all the lovers were as inspirational as she proved - Freda Strindberg, widow of the dramatist, was meant to be a one-night stand, but turned into an early version of Glenn Close in Fatal Attraction, pursuing John around London and Paris, threatening to kill herself or him, and harrassing him to the point where he could do no work.
Such stories are gripping and it is easy to see why Holroyd has been credited with raising biography to the level of fiction; yet by pitching his portrait of John at the level of a roaring boy, without the counterbalance of his art, we are left with a creature wild to no purpose and selfish beyond belief.
If Holroyd felt that analysing works of art was not his forte, then such modesty is discounted by the skills he displays on the rare occasions where he does allow himself to comment on one of the works. His description of how, by using the point of a very hard pencil, John was able to give his portrait of Epstein "a taut quality, a tightness of face and mouth indicating both intellect and temperamental force", says much neatly, and makes it doubly irritating that it is almost halfway through the book before the art is allowed to move centre stage and then only because of the crisis that was to wreck John's reputation. It began with Roger Fry's first Post-Impressionist exhibition in 1910 which introduced the English to Gauguin, van Gogh and Cezanne and divided the London art world down the middle. It was John's refusal to participate in Fry's second show in 1912 that led to his rejection by the new supporters of modernism while leaving him no more acceptable to the traditionalist camp, for whom he remained the loose-living radical of his glory years.
So the decline began and Holroyd is especially moving on John's life as an increasingly isolated society portrait painter for which he seems to have been hilariously unsuited - irritating famous sitters like Lloyd George or making them fidget hopelessly as he did with Churchill. The nadir was reached in 1920 when the soap tycoon Lord Leverhulme cut up a hated portrait and sent the off-cuts back to John. The story was played up by the press, provoking art-school riots in London and Paris, and a procession to the Piazza della Signoria in Florence where a statue of Leverhulme, carved out of soap, was publicly burned - the only time John had the warm support of the younger generation.
It wasn't all enmity - Thomas Hardy said he was happier to see his portrait by John in the Fitzwilliam than he was to have won the Nobel prize - and such forceful support makes one long to find more such works singled out and explained in depth. Holroyd quite rightly identifies the Tate's portrait of the cellist Madame Suggia as one of the artist's most ambitious works, though by confining himself to the factual details of how and where the work was produced, what the painter and the sitter thought of each other and for how much the canvas was finally sold, he leaves the reader impatient to know what exactly it was that John did that makes the thing worth all this attention.
When Gauguin painted the cellist Fritz Schneklud in 1894, the portrait was hailed as a rare attempt to convey the effect of music graphically, using lines that radiate out from the figure in the way that radio waves would later be depicted in cartoons. As Holroyd has already told us that John admired Gauguin, it is reasonable to infer that he was attempting a similar solution through the ripples in the drapery swelling behind his cellist, though the real acoustic force seems to emanate from Suggia's long robe whose acetate red pulsates with sound, making it the only dress in the history of art that you can hear. Of the two, John's seems to me the most successful painting, full of passion and wit. Holroyd claims to have used the paintings to illumine the life, one wishes, just occasionally it had been the other way round.
Inevitably, this tale of early promise unfulfilled ends sadly. There was too much drink and the once romantic Bohemianism looks worn and bitter in a cantankerous old man. After World War II, the offer of a knighthood was snatched back when the Palace discovered that John had never formally married Dorelia. He went down on one knee to propose but she proudly spurned the idea. John died in 1961 just as the rest of the population was starting to have the sort of sex-life he had enjoyed for over three-quarters of a century - in that at least he was always in the avant garde.
At the end he was not quite the old dodo many assume - one of his last acts was to leave his sick-bed to keep a promise to Bertrand Russell that he would sit down in Trafalgar Square in protest against nuclear weapons. It was quite an experience - he had not seen so many people gathered together since Mafeking Night, though his era was by then so long gone that no one amongst the young demonstrators had any idea who he was.