[1] In 1857 he was chosen as a candidate to contest the two-seat constituency of Finsbury as a Whig and supporter of the policy of Lord Palmerston.
He lost his seat, with The Standard noting satirically that: "...the honourable gentleman neither spared his lungs nor his powers of sitting out the most long-winded debate...
He had almost arrived at the distinction of being called a bore... Happily for his peace, his health, and his pocket, his too Liberal career has been stopped by an oblivious constituency".
[4]On 13 November 1861 one of the sitting members of parliament for Finsbury, Thomas Slingsby Duncombe, died.
[11][12] William Cox is buried in the parish of St Andrew's churchyard, Netteswell, Harlow.