He was born in Westminster, the eldest son of politician Richard Benyon, of Gidea Hall in Essex and Englefield House, Berkshire, and his wife Hannah Hulse, the eldest daughter of Sir Edward Hulse, 1st Baronet of Breamore House, Hampshire.
In 1814, after succeeding to the estates of his half-uncle Powlett Wrighte of Englefield House (who had died in 1779) he assumed the name of Richard Powlett-Wrighte.
His land agent was Robert Todd and his head gardener was William Armstrong and these two men dealt with day-to-day work on the estate, particularly when Benyon was not in residence.
New flint and brick estate workers' cottages were under construction at Culford, as can be seen in letters between Benyon de Beauvoir and Robert Todd.
The dwellings won an award for their sensible design; they still stand along Main Road, Culford, today, surrounded by their large gardens.
However, in December 1840, Benyond de Beauvoir shut down Culford's public house, The White Hart (now known as Benyon Lodge), because he regarded it as "a scene of moral debauchery".
When the Royal Berkshire Hospital was founded at Reading in 1839, Benyon contributed the huge sum of £5,000 (equivalent to £556,000 in 2023) and, by his liberality, aided materially in the formation of that invaluable charity.
He married, on 27 September 1797, Elizabeth the only daughter of Sir Francis Sykes, Bart, of Basildon Park in Berkshire.
The Chancery Court decided that the estates were vested with the four surviving daughters of the deceased sister but would not pass to their heirs.