John Breedon I was born in 1622, probably in Woburn (Bedfordshire). He was the third of thirteen children of the Rev. Zacheus Breedon of Woburn and, later, of Croughton (Northamptonshire) by his wife, Margery daughter of Rev. John Burges. His elder brother was the Governor of Nova Scotia and Arcadia, Capt. Thomas Breedon.

He was apprenticed as a tradesman in London at the age of thirteen. About 1657, John married Mary, the daughter of John Brumpstead. She was fifteen years his senior. They had one son, Orlando, a year later. Orlando later attended Brazenose College, Oxford, but died probably in his early twenties. In 1648, John became a freeman of the Ironmongers' Company. He was appointed commissioner for assessment in Westminster in 1660. He became an alderman of the City on 23rd July 1667 and master the following year. In 1663, he had been left some land in Aspley Guise (Bedfordshire) by his father, but by 1671 he had amassed enough of a fortune in the City to purchase for himself a country estate from the son of Sir John Davis. This was Bere Court in Berkshire and he thus became lord of the manor of Pangbourne. He continued to buy and lease property over the next decade, for example at Hartwell and Stone, Rickmansworth, Westminster and in County Durham. In 1675, he was appointed High Sheriff of Berkshire and in 1675 was a Commissioner for assessment again for three years. John became a JP in 1680 and a Freeman of the Borough and Tory Member of Parliament for Reading in 1685. He died on 16th August 1685 and was buried in the chancel of Pangbourne Church. His estates were inherited by his grand-nephew, John Breedon II.