His father was raised to the peerage in 1641 and he died fighting for the King in the civil wars in 1649 as one of the commanders of the Colchester garrison.

[1] Henry's eldest brother was Arthur Capell, 1st Earl of Essex.

Capell was re-elected MP for Tewkesbury in the two elections of 1679, was a member of the English Privy Council, from 22 April 1679 to 31 January 1680, and was First Lord of the Admiralty, between 1679 and 1680.

His term as Lord Deputy was not considered successful because of him being a firm Whig and presiding over an administration which was deeply divided between Whigs and Tories, and he did nothing to help this situation change.

Capell died aged 58 in Chapelizod, County Dublin, and was buried on 8 September 1696 in Little Hadham, Hertfordshire.