She was the daughter of a bootmaker and the granddaughter of the owner of the Castle Hotel in Brighton. At the age of fifteen, she ran off with Jem Mason, a well-known jockey, to live with him in London. As his red-headed mistress and an aspiring actress, she renamed herself Harriet Howard and was referred to as Miss Howard. At the age of eighteen, her next lover and patron was the married Major Mountjoy Martyn, Life Guards. Miss Howard bore him a son, Martin Constantin Haryett, who at his baptism was presented as the child of her parents. The grateful Major Martyn bestowed a fortune on her and their son. At a party given by Lady Blessington in 1846, Miss Howard met Louis Napoleon, pretender to the throne of France, but at that time exiled in London. He moved in with her. With her wealth, she supported his efforts and conspiracies to return to France. Napoleon brought his two sons from an affair at the prison at Ham into the household, where they were educated along with Martin.
Paris
In 1848 Napoleon returned to France and eventually became President. Miss Howard with the three boys moved to the rue de Cirque adjacent to the Palais de l'Élysée, where she kept herself in the background as his mistress. She had a powerful enemy in Napoleon's cousin Princess Mathilde to whom he was once engaged and who also had supported him financially. Miss Howard continued to support his aspirations to become emperor and largely financed his 1851 Coup d'état. One year later, after a confirming plebiscite, he became Napoleon III, Emperor of the French. Soon, he was on a search for an empress, and Miss Howard found herself cast aside. Napoleon, after having been rejected by Carola of Vasa of Sweden and other high-standing members of the nobility, chose Eugenie de Montijo. Miss Howard was sent away to Le Havre when Napoleon announced this marriage, and her secretary desk was emptied of its compromising letters.
Miss Howard's fortune was built up again, as Napoleon repaid his financial obligations. She was given the title comtesse de Beauregard, owner of the Château de Beauregard near the main route between La Celle-Saint-Cloud and Versailles near Paris. Within six months of the marriage, Napoleon resumed his relationship with her. His wife, who found sex "disgusting", forbade him to see her, and he, being in need of an heir, had to submit. Eventually in 1854, Miss Howard married Captain Clarence Trelawny, an English horse breeder who used her money for his business. The two sons of Napoleon she helped to raise returned to their mother. However, Harriet and Clarence's marriage was difficult and did not last – they divorced in 1865, the same year she died. The relationship to her son Martin was also strained – at his 21st birthday party, he asked her publicly: "Now that I'm grown, Mother, won't you tell me who my father was?". Martin was later made comte de Béchevêt by Napoleon III, married into Hungarian nobility and had three children, Richard Martyn Haryett de Béchevêt, Grisilde Charlotte Haryett de Béchevêt and Marianne Josephine Haryett de Béchevêt. When Martin died in 1907, his son Richard inherited his title. She died in her castle on 19 August 1865 at 6:30 pm. She is buried alongside her son in the cemetery of Le Chesnay, located less than 900 metres from the château.
