Watson was born in Kent. He was a Fellow of Emmanuel College Cambridge where he married Elizabeth Savage, the daughter of the Master. After her death at Little Sampford in 1736, he was left to bring up two daughters. In his Story of the Sampfords, Gerald Curtis relates that the daughters – one married to a Suffolk parson and the other to the former Lieutenant-Governor of Surat in the East Indies – commemorated their parents on a tablet in the chancel of Little Sampford church.
Watson was already rector of Little Sampford when he was appointed to the livings of Hempstead and Great Sampford. However, it seems that although he hired a curate to look after Hempstead, he left Great Sampford even more neglected. After a visit in 1759, the curate of Thaxted wrote in his diary that
Ye Church at Gt Sampford does not look like a ‘house of prayer’ nor the vicar like ‘a man of God’. Ye inhabitants forget to repair ye church and ye vicar forgets to instruct his parishioners. Ye vicar’s name is Watson: his ill-conduct and dissolute behaviour is universally known and he, with great justice, is universally detested. His own Clerk’s account to me is characteristic: Sir (says ye clerk) our vicar makes nothing of missing ten, twelve, sometimes twenty verse at a time when he reads ye lessons.