Over 150 years after her birth, 109 years after mounting the British throne alongside her husband, George V, sixty-six years after her death, Mary of Teck has gone viral. Until the publication last year by the tiny Zuleika press of The Quest for Queen Mary, the grandmother of Elizabeth II was a dim, distant figure, remembered, if at all, for her fabled habit – and fabled it seems to have been, for it does not surface in either of these books – when staying as a house guest of showering such compliments on whatever object or bauble fell within her gaze that its owners would feel compelled instantly to gift it to her.

But now Queen Mary is all the rage. That avid reader (or, more to the point, listener, for she preferred her ladies-in-waiting to do the reading while she reclined on a sofa with cocked ear) has come back to life as a publishing phenomenon. Within a few months of its appearance last year, the royal scrapbook of James Pope-Hennessy, himself dead these forty-five years, had become the talk of country house literary festivals and a bulwark of bookshop counters (an upgrade to The Wicked Wit of Prince Philip).

It has now been snapped up and republished by Hodder & Stoughton, which this month has also resurrected Pope-Hennessy’s long-out-of-print Queen Mary: The Official Biography of 1959, the raw materials for which, gathered by Pope-Hennessy as he crisscrossed Europe in pursuit of her relatives and acquaintances, are contained in The Quest for Queen Mary.

If the recent renaissance in Queen Mary studies has quietly euthanised one old tale, a host of others have risen in its place. The Quest for Queen Mary has given us Queen Mary the Motoring Enthusiast, Queen Mary the Ivy Killer and Queen Mary the Existentialist (she seems particularly to have admired Crime and Punishment). There are moments in the book of parody-defying magniloquence: Queen Mary, for example, announcing to a woman of the bedchamber, ‘I should like to die to the sound of a military march.’ And there are unanticipated streaks of bathos: the compulsively punctual Queen Mary being driven slowly around the streets of Leatherhead to ensure that she did not arrive early for a tea party.

The woman who emerges from the official biography and from the collection of interviews and offcuts is in essentials the same one: a person of iron self-discipline, blessed with a sacerdotal sense of duty. Queen for twenty-six years from 1910 and queen mother for another seventeen after George V’s death in 1936, Mary was to her contemporaries a marmoreal figure, the same upright jewel-laden person, tiara resting on her water spaniel’s fringe, at eighteen and eighty. ‘Stately’ and ‘imposing’, Pope-Hennessy says, were the adjectives most commonly associated with her.

But there are subtle changes of register between the two books. While in the biography the emphasis is on public virtue, such as Mary’s charitable endeavours and the tireless support she gave her husband, in The Quest for Queen Mary the private defects at least balance these out. Her coldness is a recurring theme, as is her tendency to abandon long-standing friends who were inconsiderate enough to fall ill or grow old. In the biography Pope-Hennessy skirts over Mary’s parenting skills, but his interlocutors were clear that she was an indifferent mother. A member of her household explained to him, ‘she put The Throne above everything else and all personal feelings’. Characteristically, she refused ever to meet Wallis Simpson, whose marriage to her eldest son, the Duke of Windsor, almost uprooted the monarchy.

Mary of Teck was born at Kensington Palace in 1867. Her cantankerous, precedence-obsessed father belonged to a morganatic branch of the royal family of Württemberg. Her mother, a jovial, extravagant and hopelessly disorderly woman known to the public as ‘Fat Mary’, was a daughter of the Duke of Cambridge, George III’s seventh son. Her illustrious ancestry notwithstanding, Mary endured a straitened upbringing by royal standards. Her parents’ perennial indebtedness meant they could live no closer to London than White Lodge in the depths of Richmond Park, a gift from Queen Victoria. For a time during Mary’s childhood, the Tecks left Britain altogether in an attempt to economise.

Money may have meant a lot, but pedigree still counted for more. According to British (though not German) standards, Mary of Teck was impeccably royal, and that meant marriageable. By the late 19th century, Queen Victoria had arrived at the view that marital unions to bolster international alliances brought more trouble than advantage. Yet the notion that an heir to the throne might wed a commoner was still some way off. When, in the early 1890s, thoughts turned to finding a wife for the Duke of Clarence, second in line to the throne after his father, the Prince of Wales, Mary of Teck was one of the few available princesses to be free of inconvenient foreign allegiances while also having blood an appropriate shade of purple. After inspecting Mary at close quarters at Balmoral in 1891, Queen Victoria declared herself satisfied that this ‘dear, charming girl … so sensible & unfrivolous’ would make a suitable wife for her diffident, ineffectual grandson.

Of course, it was not the Duke of Clarence whom Mary married. Only six weeks after their engagement, the lackadaisical duke expired and Mary was swiftly engaged to his younger brother, George, Duke of York. If memories of the miseries endured by an earlier princess betrothed successively to two heirs to the throne, Catherine of Aragon, flickered across her mind, it is not obvious from these books. Indeed, Mary seems to have been impervious to thoughts of a turbulent kind, especially if they concerned the royal family, for whom she believed ‘the Almighty has a special providence’.

Mary and George married in 1893. As Pope-Hennessy makes clear, the success of the union, which was marked by notable fidelity on both sides, owed in no small part to Mary’s devotion to the institution of monarchy. This led her to endure her husband’s combustible moods, his mania for massacring defenceless birds (Mary was a decidedly urban queen, with little enthusiasm, unlike her descendants, for the countryside, or indeed Scotland) and the day-to-day dullness of his court. In fact, devotion to the cult of royalty seems to have coloured every aspect of her life. The measure of an artwork’s value, therefore, was not its beauty or originality, but whether or not it had been connected with some royal personage of the past. Even teatime presented an opportunity for displays of familial piety, with the regular serving of ‘Biscuits Saxe-Weimar’.

While Mary might have seemed changeless, the institution of monarchy was changing around her. Mary and George’s marriage was to be the last union of equals in the upper echelons of the royal family, a point made with a mixture of pride and abandon by the baseball-capped and gumbooted Duke of Windsor when Pope-Hennessy paid a visit to him in France in 1957, the account of which is the most entertaining episode in The Quest for Queen Mary: ‘You realise there are only three completely royal persons alive now? My sister, my brother and myself.’

What is more striking still, particularly over the length of the official biography, is the Englishing of the royal family during Mary’s lifetime. The process was hastened by the First World War, but it was already apparent – to her dismay – to Queen Victoria in 1891, when she noted that Edward VII’s children were ‘very exclusively English … & this is a great misfortune in these days’. In Mary’s youth, there were almost annual trips to relations in Stuttgart and Reinthal, Strelitz and St Moritz. But in the last twenty-eight years of her life she did not once leave the British Isles, and in 1941 could even be found writing, ‘how I hate the Germans’ – a people she had grown up among and to which she half-belonged. Beside Lake Constance, in Gmunden and on trains conveying him to meet the relicts of one more ex-sovereign, Pope-Hennessy felt this change acutely. Philipp, Duke of Württemberg, confided in him that by the 1950s the British royal family had stopped answering letters from German relations altogether.

And who was this character who moved so silkily among postwar European royalty, the rhapsodist of their twilight years? In his efficient introduction to The Quest for Queen Mary, Hugo Vickers gives us the bare bones: a Catholic, a homosexual, a consummate networker, a friend of artists and writers. But he remains throughout the two books as elusive as Queen Mary is inescapable, alternately ingratiating and acerbic, mawkish and mordant, verbose and concise. Elizabeth II found him ‘cold’. Grand Duchess Xenia of Russia laboured under the impression that his name was Poke-Henderson. And what of Queen Mary? She met him once, briefly, at a party in Surrey in 1949, four years before her death. In her diary, Queen Mary listed the guests by name, but she faltered when she got to her future biographer, managing only ‘and ?’.