His mother was Mary, daughter of Marcellus Rivers of St. Saviour's, Southwark, and Rivershill.

He left Oxford without a degree, and in 1654 was entered a student of the Middle Temple (Gardiner, Wadham College, p. 198).

In 1655 he was sent to Exeter gaol on a charge of complicity in the rising against the government at Salisbury of John Penruddock (see State Papers, Dom.

His father petitioned the council to pardon him on account of his youth, and General Desborough was ordered, after taking security from the elder Reynell for his good conduct, to send him home.

In 1657 he succeeded to his patrimony of Rivershill, and in 1661 greeted the Restoration with an extravagant ode, ‘The Fortunate Change, being a Panegyrick to his sacred Majesty King Charles II,’ London, 1661, fol.

Reynell's economic study resulted in ‘The True English Interest, or an Account of the Chief Natural Improvements and some Political Observations demonstrating an Infallible Advance of this Nation to infinite Wealth and Greatness, Trade and Populacy, with Employment and Preferment for all Persons,’ London, 1674, 8vo (licensed 5 Sept. 1673).