Lambton was born into a politically distinguished family whose wealth was derived from the coalmines surrounding Lambton castle in county Durham. His father, William Henry Lambton, was MP for Durham City, 1787-97, and his eldest brother, John George Lambton, who became the first earl of Durham in 1833, was a son-in-law of the prime minister Lord Grey and an instrumental figure in the drafting of the reform bill.
At the 1832 general election Lambton offered for the newly-created division of North Durham. Following a keenly fought contest in which he called for ‘the correction of all those abuses which inflict so much misery on the state’, he decisively headed the poll.
At the 1835 general election, Lambton unambiguously nailed his reformist colours to the mast. He advocated the ballot, triennial parliaments and household suffrage, and declared that ‘I would rather trust a child to a ferocious tiger than I would trust the working-out of the Reform bill ... to a Tory administration’.
Lambton opposed Melbourne’s ministry, however, over the established church bill, believing that the legislation would lead to a misuse of the revenues of the Durham see. Declaring that Lord John Russell was ‘unacquainted’ with the ‘nature of church property in Durham’, he unsuccessfully pressed for a delay in reading the bill, 8 July 1836, and his motion to insert a clause to stop the appropriation of the revenues of the Durham diocese was defeated 88-8, 12 July 1836. He did, though, back the revised ministerial plan for the abolition of church rates. While maintaining his belief that the bill was ‘harsh and unjust on church leaseholders’, he stressed that ‘the Dissenters came before Parliament with very strong claims to its generous and cordial support’, 22 May 1837, and ‘any objections ... were matters for future consideration’, 23 May 1837.
Comfortably re-elected at the top of the poll at the 1837 general election and returned without opposition in 1841, Lambton finally found his feet as a debater in the early 1840s, and he frequently spoke on ecclesiastical matters, particularly to defend the revenues of the Durham see and the rights of leaseholders of church property. He intervened to back the ministry’s ecclesiastical duties and revenues bill, 6 Apr. and 29 June 1840, although his proposed amendment to ensure that church revenues were only appropriated to the diocese to which they belonged (which was essentially a repeat of his previous defence of the extremely wealthy Durham bishopric) was defeated 50-15, 9 July 1840. Following his service on the 1837-38 and 1839 select committees on church leases, when he was an assiduous questioner of witnesses, he intervened in the debates on the Southwark improvement bill, urging the government ‘not to sanction any compulsory sale of church leasehold property without a clause to ensure compensation to the church lessees for the right of renewal’, 26 Apr. 1842.
Lambton also spoke on matters affecting his family’s commercial interests. An active member of numerous select committees on the coal trade, he criticised Peel’s ministry for its proposed new tariff on coal, arguing that ‘it would only aggravate foreign competitors into retaliating’, 14 June 1842, but intervened to support the government’s mines and collieries bill, 22 and 24 June 1842.
Following his departure from the Commons, Lambton faded into relative obscurity. He died without issue at his residence at 8 Lansdowne Place, Brighton, in 1876. His estate was valued at £25,000.
