It is perhaps useful to remind visitors to Tate Britain's new exhibition, Picasso and Modern British Art, just how long ago Picasso was and how, in this particular context, the term Modern British is stretched to embrace the full century from Duncan Grant, whose first tame and tentative Picassian experiment was made in 1912, to David Hockney, who is still occasionally Picassian now.
Picasso was born in 1881 when Victoria had two more decades on the throne ahead of her, British forces were withdrawn from Afghanistan, Gilbert and Sullivan presented Patience, and Lord Leighton was president of the Royal Academy.
He died in 1973, all but 40 years ago, when the Cold War was an ever-present threat, Britain joined the European Economic Community, our economy was wrecked by a cartel of Arab oil-producing countries, Hockney was into his first maturity and the infinitely forgettable Tom Monnington was PRA.
In his 90-odd years Picasso had been fin-de-siècle, had worked his way through the enchantments of periods Blue, Pink and Iberian-Negro (a term coined by Christian Zervos, his apologist), through Cubism Analytical and Synthetic, Classicism and Surrealism and into the violent distortions that succeeded Guernica (though never matching its sincerity), on and on through an astonishing range of whimsical diversions in every medium and visual quips at the expense of Velázquez, Rembrandt, Delacroix and Ingres, declining into a final phase so crude, genital and urinophilous in imagery that his friend Douglas Cooper dubbed him an old fool in the ante-chamber of death.
Early admirers in England, slavish, seeing him take himself so seriously, took him seriously too; others, including Winston Churchill, Evelyn Waugh and a posse of Royal Academicians, would have kicked his arse; and between these lay what inexorably became a vast majority - all those incapable of thinking for themselves and anxious not to be wrong-footed by Mrs Grundy, who decided that adulation was a safer bet than arse-kicking. This is still the status quo.
Picasso was first presented to the British public in the winter of 1910-11 by the critic Roger Fry, the Saatchi-Serota of his day (though without the cash). After the hiatus of the First World War, with the Tate a Vale of Lethe and the Academy mounting only its Summer and Winter Exhibitions (the latter always art historical), our awareness in the Twenties and Thirties of what was happening abroad in art in general and with Picasso in particular, depended almost entirely on exhibitions mounted in brave small dealers' galleries - a handful only, but persistent- even during and after the Second World War.
There were two exceptions: the now notorious Surrealism Exhibition at the New Burlington Galleries in 1936, which included 11 works by Picasso, and spawned an increasingly political debate that lasted into the 1950s; and in January 1939, the exhibition at the Whitechapel Gallery of Guernica and 67 related paintings and studies; hanging for only two weeks, it was seen by 12,000 or 15,000 visitors (recorded figures vary).
This drip, drip of exposure - to which must be added his work for the Ballet Russe in London in 1919 (10 weeks a resident at the Savoy) and the ease with which the bright young things of the London art world could spend time in Paris, the rate of exchange madly favourable, meant that towards the end of the 1930s Augustus John could write enviously of Picasso as having "the greatest snob-following of our time".
This was true, but not wholly and only so. After six years of war, when our clothes were threadbare or hand-me-downs and our bellies empty on the shortest rations since the Rape of Poland, 160,000 of us queued in the bitter winter of 1945-46 to see a Picasso and Matisse exhibition mounted at the newly reopened Victoria and Albert Museum, and very few of these were snobs.
There were 30 paintings by Matisse, and by Picasso 25, all but one lent by himself and painted during the war. They were not the best - the very best of him was in Guernica and that intensely dramatic, symbolic and soul-exposing painting had so drained him that never again could he reach its emotional pitch, never once throughout all the horrors of the war, living in occupied Paris, watched all the time by Nazis, could he raise his game to take emotion further and, into his sixties, having nothing more to say, he was emasculated.
The young among the 2,500 who every day queued to see his 25 paintings could not bring themselves to admit such a falling off and, revering Picasso's reputation, sustained it in blind faith in terms then, and still, quite meaningless: so too did his old apologists and sycophants, with, in the end, only Douglas Cooper telling the unvarnished truth.
The arse-kickers were vanquished - and rightly, for their view was based on cussed misunderstanding of Picasso at his greatest, as Cubist, Classicist, Surrealist and the excoriating painter of Guernica, all beyond their comprehension; but had they acknowledged him for his first 40 years of enquiring experiment and achievement, and damned him for the slough of capricious, whimsical, skittish, teasing, clowning, erratic and mercurial nonsense into which he fell, we might now have a truer view of him.
Tate Britain's exhibition is an exploration of Picasso's influence on seven English contemporaries, with Duncan Grant, Wyndham Lewis, Ben Nicholson, Henry Moore, Francis Bacon, Graham Sutherland and David Hockney, pars pro toto, for a hundred more.
He trumps them all and even with the worst of paintings so dominates the show that he is a Nureyev dancing among amputees, a cruel spectacle as we are introduced first to the shallow mimicry of Grant, and last to the triviality of Hockney. "Damn him, how various he is," as Gainsborough once said of Reynolds, but 'twere far better said of Picasso, who in 1901 could perfectly conjure the sweet spirit of a child and fill a vase of flowers with consummate vulgarity, in 1905 evoke the hesitancy of a girl on the brink of womanhood, then plough through the intellectual (and ultimately fraudulent) complexities of Cubism and give us, in 1923, a woman of Roman antiquity clad in a chemise, the form, texture and transparency of which reached the canvas in a flurrying cat's cradle of loose brushstrokes as though Cubism, in none of its forms, had ever been invented. Again and again we must be astonished by his capability - never more so than in the room devoted to Moore, where all the sculptor's figures, bulky and contrived, are trounced by Picasso's Nude Seated on a Rock, no more than the size of a postcard and painted with the delicacy of breath, yet simply, grandly, wonderfully monumental.
This is a useful exhibition and visitors should see the chosen British artists (and others of their periods) in a new light. Lewis so swiftly escaped Picasso's influence to develop entirely independent semi- and post-Cubist mannerisms that were peculiarly his own, that he seems not to merit a place in it (his Theatre Manager of 1909 surely embodies the anti-Semitism that burgeoned in his political writing between the wars, rather than the supposed influence of Picasso's Demoiselles d'Avignon).
Nicholson began his Picassianism as a plagiarist, developed a very English scrubbed and scruffy decorative variant of Cubism, and moved on to heavyweight experiments in dark tone, interlocking flattened forms and profiles and scratched (sgraffito) outlines; for him Picasso was a nourishing rather than an overwhelming influence, soon to be discarded. Moore, on the other hand, was overwhelmed - "I am Moore," Picasso could justifiably have said. Never in such thrall, Bacon's essential Picassianisms were few and date from years when he was less a painter than a designer of furniture and carpets, and he soon escaped the influence.
As for Sutherland, his landscape impertinently titled Homage to Picasso of 1947 is so lacking in the power of the old master as to seem a feeble insult (though it may be a useful document); in other examples he adopts the idiom but seems not to understand it. Hockney's response to Picasso - whom he did not meet - provides the weakest chapter of the exhibition and is far better illustrated by the Bridlington guru's variations on a painting by Claude now assembled in the Royal Academy.
I must end with a note on Picasso's development, for he is the dominant figure and fons et origo here. The visitor with a sharp eye will observe that over a long period his various stylistic mannerisms overlap or are recovered from the past.
In an interview in 1923, published under the title Picasso Speaks, he claimed that the "several manners" to which he admitted should not be seen as evolution but as particular responses to the subject or occasion: "Whenever I had something to say I have said it in the manner in which I have felt it ought to be said. Different motifs inevitably require different methods of expression."
Picasso & Modern British Art is at Tate Britain, SW1 (020 7887 8888, tate.org.uk) until July 15. Open Sat-Thurs 10am-6pm, Fri 10am-10pm; admission £14 (concs £12.20).