Synnott, Thomas Lambert (1810–97), workhouse guardian and prison governor, was born probably in Dublin, eldest son of Thomas Sinnott, vintner, of 59–61 Barrack St., Dublin. Though there is evidence his father belonged to the Church of Ireland, Synnott was brought up Roman catholic, which suggests that his parents’ marriage was of mixed faith; no other details of his mother are known. In c.1835 he was established as a grocer in 60 Barrack St.; the family business moved to Ellis Quay c.1840. He took his first steps in local politics by attending the vestry meetings of the parish of St Paul's in the later 1830s and was elected to minor office for several years running. In April 1839 he acted as one of the leading personalities on the popular side during conflict over the applotment of vestry cess in St Paul's. He had formed alliances with minor figures in the repeal movement in the city, mostly middle-ranking shopkeepers and solicitors. He changed the spelling of his surname, presumably to lend some mystique to his social background.
In May 1839, at a meeting of ratepayers dominated by a repeal clique, he was one of three candidates nominated for election to the North Dublin poor law union. His election address voiced dissatisfaction with the sectarian imbalance in local administration. Elected to the board of guardians at his first attempt, he attended diligently and displayed some skill in financial debate and deliberation. Like many of his fellows he expressed resentment at the propensity for intervention and managerial control of union affairs shown by the poor law commissioners. He was reelected in 1841 and 1842, his final year in office. As one of the spoils of victory by the repeal interest in the Dublin municipal elections in 1840, he was rewarded for stalwart support with the sinecure (worth £100 a year) of high constable and billet master for the city of Dublin, ousting a noted tory in the process. He held the office until 1848. Between 1839 and 1843 he participated, often in committee, in a series of nationalist city demonstrations, helped to raise petitions for issues of moment, and did back-room work during elections and in the organisation of the O'Connell (qv) tribute. He became a repeal warden in 1842–3. In October 1843 he was chosen to warn the Drogheda public that the proposed monster meeting due to take place in Clontarf had been proclaimed.
His dedicated relief work during the famine (1845–9) outshone his previous activities. Invited to take the office of secretary to the Mansion House committee in September 1845, he issued questionnaires on distress to clergymen of all denominations. He collated and meticulously analysed the replies, and was praised for the efficiency of the work, which showed irrefutably the severity of the distress in most of Ireland. He was next drafted as secretary to the Indian Relief Fund, established in January 1846. In this case his work involved assessment of need and the distribution of relief by parish in areas of greatest misery. Keeping accounts in dealing with some 2,000 applications in a time of great distrust of relief operations, he was praised for the clarity of his financial statements and the extreme economy of the administrative effort. Appointed assistant-secretary to the Central Relief Committee (December 1846), he was concerned in the distribution of £84,000 in relief between January 1847 and May 1849; his responsibilities were onerous and grave, and it is likely that he was one of the most influential of committee members, if only by default, as he attended meetings with unusual regularity. Archbishop Daniel Murray (qv) admired his businesslike habits and moral character, and during 1849–50 Synott continued to work for Murray, putting his vast knowledge of rural destitution at the service of the archbishop.
Though Synott never acquired much of a public profile, his contribution to famine relief was of immense value. It is likely the patronage of influential persons on these relief committees got him the job of governor of the women's prison at Grangegorman in May 1848. Demarcation disputes with the matron of the prison, which he had not the legal resources to win, soured his possession of office. Though he made the best of things until the early 1860s, he antagonised authorities in the prison service by granting favours to Margaret Aylward (qv) during her controversial detention at Grangegorman in 1860–61. As a result he was victimised by the prison inspectorate inquiring into a series of petty complaints arising between 1861 and 1865, and finally dismissed in August 1865 by the lord lieutenant, without right of appeal, for alleged negligence. After fighting unsuccessfully in the court of equity to have the decision reversed and his pension confirmed, he sank from public view. He retired to 17 Tritonville Road, Sandymount, in 1872, where he died 17 December 1897, leaving effects of a mere £9. 4s. 6d. to his son, a horse-dealer.
He married first Marianne Synnott (1818–55), and married secondly in the later 1850s. He had at least six children, two of whom died in infancy.