Haddock, the second son of Admiral Sir Richard Haddock, was destined for a naval career from childhood and first distinguished himself at the age of 16 as a midshipman at the Battle of Vigo in 1702. Promoted to lieutenant, he served at the relief of Barcelona in 1706, and at the Battle of Cape Passaro in 1718, he was Captain of the 70-gun Grafton, and led the attack. In 1732 he was appointed to command of The Nore.
He was Commander-in-Chief in the Mediterranean from 1738 to 1742. After the outbreak of the War of Austrian Succession, with only 10 ships at his disposal, he was unable to prevent the crossing of two Spanish armies from Barcelona to Italy. In November 1741, a Spanish fleet with 14,000 troops sailed to Orbetello and in mid-December, 52 ships carrying almost 12,800 men successfully crossed towards La Spezia. Only with the arrival of additional ships from Britain in February 1742, he was able to successfully blockaded the Spanish coast and take valuable prizes including two treasure ships, but failed to force the Spanish fleet into an action. He was recalled from the Mediterranean in April 1742 and succeeded first by Richard Lestock and then Thomas Mathews. He was promoted to Vice Admiral in 1741 and to Admiral in 1744.
- Nicholas (1723–1781), his heir, who followed him as MP for Rochester
- Richard (not to be confused with Richard Haddock (1673-1751), Nicholas's Brother, who became Comptroller of the Navy)
- Portrait of Nicholas Haddock, at the National Maritime Museum
- Portrait of Nicholas Haddock, at the National Portrait Gallery
- Concise Dictionary of National Biography (1930)
- Robert Beatson, A Chronological Register of Both Houses of Parliament (London: Longman, Hurst, Res & Orme, 1807) 
- The History and Topographical Survey of the County of Kent: Volume 5 (1798)
- Leigh Rayment's Historical List of MPs [self-published source][better source needed]
- Reed Browning, The War of the Austrian Succession, p. 79-81.
- Reed Browning, The War of the Austrian Succession, p. 97.
|Parliament of Great Britain|
Admiral John Jennings
|Member of Parliament for Rochester
With: David Polhill 1734–1741
Admiral Edward Vernon 1741–1743
David Polhill 1743–1746
Admiral Sir Chaloner Ogle