Background
Lambart was the son of Oliver Lambart, 1st Baron Lambart and Hester Fleetwood.
Lambart was the son of Oliver Lambart, 1st Baron Lambart and Hester Fleetwood.
He had succeeded to his father"s barony on 10 June 1618 but as this was a title in the Peerage of Ireland, he was not secluded from sitting in the House of Commons of England. Following the Irish Rebellion of 1641, he raised a regiment of 1,000 foot guards against the Roman Catholic rebels. He was subsequently the commander of the forces guarding Dublin on behalf of Charles I in 1642.
On 15 April 1647, Lambart was created Earl of Cavan and Viscount Kilcoursie in the Peerage of Ireland, in recognition of his loyalty to the Royalist cause.
Lambart married Honorary Together they had three children.
2nd Parliament of King Charles I]
He served as the Member of Parliament for Bossiney in Cornwall in 1626, and again between 1628 and 1629. Lambart was Seneschal of Cavan and of Kells in 1627 and made a member of the Privy Council of Ireland.