For the rest he was doomed to flit uneasily between two worlds: belonging to both, altogether at home in neither.Philip Ziegler is the author of `Osbert Sitwell’ (Pimlico, 4 March, pounds 14). To Wyndham Lewis he was “a hearty who has taken the wrong turning – he has looked at pictures, he has listened to music too much, he has loved the Ballet not wisely but too well”. His fellow writers respected his achievements but could never quite conceal their belief that he was not one of them.Only in his autobiography, where he translated his ancestry into art, were the two halves of Osbert’s nature successfully resolved. Virginia Woolf mocked his “extreme uneasiness, his childish vanity always striking the two notes: rank and genius”. He was deemed a literary playboy, a dilettante – a charge which infuriated him and which was belied by his productivity and the effort he put into drafting, and redrafting, everything he wrote. His efforts to shock bourgeois society were viewed as regrettable but less deleterious than drink or drugs; he was not a real rebel, judged his publisher, Harold Macmillan; rather, a radical Whig aristocrat who a hundred years before “would have fitted in among the young aristocrats in Endymion”.To his artistic friends, his seriousness of purpose was quite as suspect. He met with some disapproval – the Prince of Wales was outraged when Osbert told him that he was abandoning the Brigade of Guards for literature – but, on the whole, tolerated.

The fact that the greater part of the writing and painting he most admired came from the very social class that he so despised was never allowed to disturb this bland awareness of his own superiority.In his West End clubs Osbert was a licensed jester, the tame house poet pointed out with mingled pride and derision. He looked down on the middle classes not primarily on social grounds but because he considered them incapable of artistic creation or even appreciation. Many “artists in embryo” have contrived to mix happily with their contemporaries. A crippling compound of arrogance and shyness was more to blame.

But Osbert’s belief that his distinction lay in his literary skills and sensibilities, and that humanity was divided into two categories, the artists and the others, was unshakeable. When the children of the local noblesse played together, the Sitwells remained uneasily aloof; conscious that they did not quite fit in but not understanding why. Only much later did Osbert conclude that he and his siblings stood alone because they were artists in embryo, “with nerves and brains created for the one purpose of a certain kind of sensitive perception”.As an explanation of their social isolation, this is hardly satisfactory. Osbert was more restrained, but the knowledge nevertheless gave him great satisfaction.Yet for Osbert this was not the only, or even the most important, element in his life. His maternal great- grandfather may have been (though probably wasn’t) the son of the Prince Regent and Lady Conyngham; his mother’s mother was definitely daughter of the Duke of Beaufort.