[1] He was educated at Eton and St John's College, Cambridge, graduating MA in 1824.

[2] Sydney was first elected to parliament for Whitchurch in 1826, a seat he held until 1831,[3] when he succeeded his father in the viscountcy and entered the House of Lords.

[4] In December 1852 he was appointed Captain of the Yeomen of the Guard,[5] Deputy Chief Whip in the House of Lords[citation needed] in Lord Aberdeen's coalition government and was sworn of the Privy Council in early 1853.

[6] He continued as Captain of the Yeomen of the Guard when Lord Palmerston became prime minister in 1855, but relinquished the position when the Liberals lost power in February 1858.

[1] The family seat of Frognal House was inherited by Lord Sydney's nephew Robert Marsham, who assumed the additional surname of Townshend in accordance with his uncle's will.