He was the second son of George Loch (d. 1786) of Drylaw, Edinburgh.
He joined the marine service of the East India company and also served as a volunteer with the Royal Navy. In 1800 he served on Lord St. Vincent’s flagship during the blockade of Brest and later that year was in the unsuccessful Ferrol expedition as aide-de-camp to Sir Edward Pellew, one of the British commanders. He made his fortune trading with China and in 1821 was elected a Director of the East India Company, a position he held until 1854, acting as Chairman in 1829 and 1833. In 1837 he was attacked and stabbed by a disgruntled former employee of the Company, who subsequently committed suicide whilst in custody.
In 1830 he was returned as Member of Parliament for Hythe along with Stewart Marjoribanks (brother of East India Company Chairman Campbell Marjoribanks), serving until the constituency's representation was reduced to one member in the Great Reform Act of 1832.
He died at Bushey Grove, Hertfordshire in February 1868 aged 86. He had married Rabina Marion, the daughter of Archibald Cullen of Middlesex, with whom he had a son and a daughter. The son George also joined the navy but died of fever at Martinique in 1848. His daughter Marion Finella married Edward Marjoribanks, nephew of the MP.
- The India list and India Office list for ... - Great Britain. India Office - Google Books
- Record of Services of the Honourable East India Company's Civil Servants in the Madras Presidency 
- "LOCH, John (1781-1868), of 18 Upper Bedford Place, Russell Square, Mdx". History of Parliament Online. Retrieved 10 April 2013.
|Parliament of the United Kingdom|
Sir Robert Townsend-Farquhar
|Member of Parliament for Hythe
With: Stewart Marjoribanks
|This article about a Member of the Parliament of the United Kingdom (since 1801), for an English constituency is a stub. You can help Wikipedia by expanding it.|