Blackwood, Helena Selina (1807–67), baroness of Dufferin and Clandeboye , later countess of Gifford, author and songwriter, was born in England (possibly in London or Tunbridge Wells, Kent), second child and eldest daughter of Thomas Sheridan (eldest son of Richard Brinsley Sheridan (qv)) and Caroline Henrietta Sheridan (née Callendar), a celebrated beauty and novelist of Craigforth in Scotland. Richard Brinsley Sheridan's loss of his fortune in the Drury Lane fire (1809) left the family in a precarious financial position, which the prince of Wales alleviated by securing Thomas Sheridan the post of paymaster general at the Cape. Helen travelled with her parents to Africa, where her father died (1817). On returning to England the widowed Mrs Sheridan was again assisted by the royal family, who provided her with apartments at Hampton Court, where she reared her seven children. Educated by her mother, Helen was (like her sisters) considered precocious and high-spirited. The children took an interest in theatricals and regularly staged dramas, which the duke of Clarence attended. Helen began writing at an early age and at times collaborated with her sister Caroline, who later became famous as Mrs Caroline Norton (qv). The Sheridan sisters were well known in London society for their beauty, and despite her relative poverty Helen married (July 1825) Capt. Price Blackwood, who succeeded (1839) as 4th Baron Dufferin and Clandeboye. Owing primarily to the Blackwood family's disapproval, their honeymoon in Italy became protracted, and it was there that their only son Frederick Temple Hamilton Blackwood (qv) was born (June 1826). On their return, they divided their time between Thames Ditton and the Dufferin estate in Clandeboye, Co. Down. Her husband's naval career meant they were separated for long periods. Ireland provided her with the material for some of her best-known songs, the most popular being ‘The Irish emigrant’, set to music by Charlotte Barnard (1830–69). Blackwood herself wrote the music for another of her Irish lyrics, ‘Katey's letter’, and similarly for several songs written by her sister Caroline. ‘The charming woman’ (1835), a satirical piece on intellectual women, was also very popular.
After her husband's death (July 1841) she established herself in London, where she became familiar with many of the leading literary figures, including Carlyle, Macaulay, Thackeray, and Disraeli. She continued to accompany her son on trips to Clandeboye, and joined him on a cruise in the Mediterranean (1858–9), during which she visited Greece, Turkey, and Egypt, and rode across Palestine on a horse. These experiences inspired her satirical parody of Victorian lady travellers, Lispings from low latitudes (1863) by ‘the Hon. Impulsia Gushington’, with her own illustrations; its title plays on her son's Letters from high latitudes (1857). She married (October 1862) her long-term admirer George Hay, earl of Gifford (b. 1822), who was on his deathbed at the time of their marriage and died December 1862. Shortly after this her play ‘Finesse’, a farcical comedy, was produced in the Haymarket Theatre, London, though she did not attend its performance. As countess of Gifford she contributed a poem to the Dublin University Magazine (1865). After a long illness she died 13 June 1867 in her home, Dufferin Lodge, Highgate, London, and was buried in the churchyard of Friern Barnet. ‘Helen's tower’ at Clandeboye was dedicated to her and provided Browning with the inspiration for his elegy, written at the request of her son. Lord Dufferin edited and published her writings posthumously. Portraits of her include those by T. Hodgetts, W. H. Mote, Camille Silvy, James Rainne Swinton, and H. Robinson (in William and E. F. Finden, Portraits of the female aristocracy of the court of Queen Victoria (1849)).