His father used his position to advance his son, first as a Clerk and then Chief Clerk at the Navy Board. In 1731 John was appointed Clerk to the Cheque and Master Muster at Plymouth. He then became Clerk of the Acts in 1744 and Joint Secretary to the Lords Commissioners of Admiralty in 1748. In 1751 he succeeded Thomas Corbett as Secretary to the Admiralty. He inherited Tapeley Park in north Devon on the death of his father in 1734. Clevland was MP first for Saltash, then Sandwich and then Saltash again.
Land & estates
In about 1750 he purchased the lordship of the nearby Manor of Bideford, then a nationally prominent port.
Marriages and children
He married three times and had six sons and five daughters:
Firstly in 1729 to Elizabeth Child, the daughter of Sir Caesar Child, 2nd Baronet , of Gwynne House, Woodford Bridge in Essex, by his wife Hester Evans of Claybury Hall, Barking, Woodford. John's father William Clevland at some time before 1700 had acquired Rayhouse, the principal estate at Woodford Bridge in Essex, which he sold in 1732 to Alvar Lopez Suasso. By his wife Elizabeth Child he had three sons and three daughters, including:
*John II Clevland, eldest son and heir by his first wife, of Tapeley, MP for Barnstaple and Director of Greenwich Hospital
*Hester Clevland, eldest daughter, wife of Captain William Saltren-Willett, Royal Navy, in 1762 Captain of HMS Warspight, who fought at the Battle of Quiberon Bay. He was the second son of Thomas Saltren of Stone in the parish of Parkham, and was the heir of John Willett of Combe, Abbotsham, barrister-at-law and lord of the manor of Abbotsham. Her grandson Col. Augustus II Saltren-Willett inherited the Clevland estates including Tapeley in 1817 on the death of Hester's brother John II Clevland.
Secondly in 1743 to his first cousin Penelope Davie, the daughter of Joseph Davie of Orleigh in Devon, by whom he had one son.
He died at Tapeley on 18 June 1763, as is recorded on his monument in Westleigh Church, as a result of having "contracted a complication of disorders" due to his "constant application to the discharge" of his office of Secretary of the Admiralty.
Monument
His mural monument survives in Westleigh Church, inscribed as follows:
"Sacred to the memory of John Clevland Esqr. of Tapley in the county of Devon who for the space of forty years served his king and country with the greatest honor and fidelity the last seventeen years of which he was joint and sole secretary of the Admiralty in which office through a multiplicity of business and his constant application to the discharge of it he contracted a complication of disorders which occasioned his death at Tapley 18th June 1763. Near him here lie also enterred Elizabeth the daughter of Sr. Caesar Child, Baronet, of Gwin in Essex, with whom he intermarried in the year 1729 who dying left issue three sons and three daughters; Penelope the daughter of Joseph Davie Esqr. of Orleigh in Devon, with whom he intermarried in the year 1743 who dying left issue one son; Sarah the daughter of Chas. Shuckburgh Esqr. of Longborough in Gloucestershire with whom he intermarried in the year 1747 who dying his widow the 5th Decr. 1764 left issue two sons & two daughters"