Gardiner, Marguerite (Margaret) (1789–1849), countess of Blessington , writer, journalist, and society hostess, was born 1 September 1789 at Knockbrit, Co. Tipperary, the second daughter and fourth child of Edmund Power and his wife Ellen (née Sheehy), both from well-established catholic families. Margaret was a precocious child whose only education, from a family friend named Anne Dwyer, ended abruptly in 1797 when the Powers moved to Clonmel, where Edmund was engaged as a corn merchant. He was appointed magistrate in Tipperary and Waterford, and became notorious for his brutality in enforcing the law. He also pursued various business ventures, the failure of which imperilled the family finances and made domestic life increasingly difficult. In March 1804 Margaret was compelled to marry Captain Maurice St Leger Farmer, an army officer stationed in Clonmel. Farmer was reputedly a violent and abusive man, and she abandoned him after three months and returned home. Her movements over the next few years remain obscure, but she spent time in Cahir and Dublin and formed a close relationship with Captain Thomas Jenkins. About 1809 she settled at the latter's home in Sidmanton, Hampshire, where she lived for five years, studying and reading widely to compensate for her curtailed education.
Around this time Margaret met Charles Gardiner (1782–1829), 2nd Viscount Mountjoy, later 1st earl of Blessington, and by 1816 she was living under his protection (he reputedly remunerated Jenkins with £10,000). The following year Captain Farmer died in a drunken fall, and on 16 February 1818 Margaret married Gardiner, becoming countess of Blessington; it was at this time that she changed her first name to Marguerite. The couple spent their honeymoon in Ireland, visiting Dublin and the Blessington estates in Co. Tyrone, before returning to London, where they settled at 11 St James's Square. Lady Blessington soon established their richly furnished home as a leading venue for London society. Though she was regarded as insufficiently respectable to be visited by society women, Lady Blessington's beauty, intelligence, and charm attracted the leading statesmen, artists, and writers of the day. Guests included Lord Palmerston, Earl Grey, George Canning, Thomas Moore (qv), Thomas Lawrence (whose portrait of his hostess was exhibited at the RA in 1821 to sensational effect), John Galt, and Samuel Parr, who reportedly coined her well-known soubriquet ‘most gorgeous’. In 1821 Lady Blessington met the charismatic Alfred, Count D'Orsay, with whom she would maintain a lifelong association. In addition to this social success she began to write, and in 1822 anonymously published her first work, a collection of four essays entitled The magic lantern, or Sketches of scenes in the metropolis. This was followed in the same year by Sketches and fragments and Journal of a tour through the Netherlands to Paris in 1821.
In August 1822 the Blessingtons, accompanied by a lavish entourage of servants, set out on a continental tour that lasted for the rest of the decade. They spent some time in France, joined by D'Orsay at Avignon, before settling briefly at Genoa, where the countess formed a close friendship with Lord Byron. In 1827, during a sojourn in Naples, D'Orsay married Lady Harriet Gardiner, the daughter of the earl by a previous marriage. The newly-weds lived with the Blessingtons, and this arrangement, particularly after the death of the earl in Paris (1829), enhanced Lady Blessington's scandalous reputation in fashionable London society. Her association with D'Orsay was the subject of much controversy and speculation, though it seems that the relationship was filial rather than sexual.
The earl's death seriously diminished Lady Blessington's income, yet on her return to London in 1830 she re-established a brilliant social salon in the extravagant surroundings of Seamore Place, Mayfair. Her circle of acquaintance widened, as the Disraelis, Edward Bulwer-Lytton, Daniel Maclise (qv), Charles Dickens, and Captain Marryat, among others, attended her soirées. Despite her strenuous attempts at social integration, D'Orsay's separation from Harriet (who ran away from her household in 1831) confirmed her exclusion from respectable female society, and induced financial worries that were compounded by her numerous family dependents. She turned to writing as a means of income, publishing society novels or so-called silver fork fiction, as well as travel books and a diverse range of journalism. Two of her novels, Grace Cassidy, or The repealers (1833) and Country quarters (which appeared posthumously in 1850), were set in Ireland. She devoted considerable time to editing the annuals The book of beauty and The keepsake, writing much of the contents herself, but also soliciting contributions from the famous guests that frequented her salon. In 1832 she met S. C. Hall (qv), who suggested that she record her friendship with Byron for his New Monthly Magazine. The resulting serial, ‘Journal of conversations of Lord Byron by the countess of Blessington’ (1832–3), attracted immense public interest. It was later published as a book, Conversations with Lord Byron (1834), which remains her most significant literary work and is still valued by biographers of the poet. Her protracted stay on the continent also provided her with material for much of her fiction, which is notable mainly for its shrewd observations of high society.
In 1836 Lady Blessington moved to Gore House, Kensington, where she continued to cultivate distinguished literary society, although her prodigious work rate exacted an increasing toll on her health. In addition to novels such as The victims of society (1837) and The governess (1839), she wrote the popular travel books Idler in Italy (3 vols, 1839–40) and Idler in France (2 vols, 1841). Despite her industry, her fiscal problems continued, and in 1849, the Irish famine having drastically reduced her income from the Blessington estates, she was declared bankrupt. She joined D'Orsay in Paris and the contents of Gore House were sold to meet her debts. She died 4 June 1849 from an apoplectic stroke at her apartment on rue du Circle, near the Champs Elysées, and was buried in Chambourcy, near St Germaine-en-Laye. Her niece Marguerite Power (qv), who for many years assisted her literary work, enjoyed considerable success in her own right as a poet and novelist.
Archives of Lady Blessington's papers and correspondence are held in New York Public Library; Princeton University Library; the British Library, London; the Bodleian Library, Oxford; and the National Library of Scotland, Edinburgh. The most famous likeness is the portrait by Lawrence (c.1820), held in the Wallace Collection, London. Lithographs by Daniel Maclise and R. J. Lane, and drawings by P. E. Ströhling and G. Cattermole, are in the British Museum, London. Several likenesses are also held in the National Portrait Gallery, London.