John Holroyd the son of Isaac Holroyd and Dorothy Baker was born in Ireland on 21^st December 1735. The name of Holroyd is of great antiquity in the West Riding of Yorkshire and is derived from the hamlet or estate of Holroyd (or Howroyd as it is pronounced in Bark-Island, six miles from Halifax). William de Howroyde possessed these lands in the reign of King Edward I. From him is descended John Holroyd's great grandfather Isaac Holroyde who went to Ireland in the reign of Charles II where he acquired considerable possessions. John's father Isaac was educated at Hackney school and afterwards at Doctor Sheridan's in Dublin before entering the University of Dublin and afterwards at the Middle Temple, London. Isaac married Dorothy , the youngest daughter of Daniel Baker of Penn, Bucks. In 1768 John Holroyd succeeded to the estates of his mother's brother, the Rev. Jones Baker, and took the name Baker before Holroyd.

John Holroyd entered the Marquis of Granby's regiment of light dragoons called the Royal Foresters in 1760 where he was Captain of a troop. When peace arrived in 1763 and the regiment was disbanded, John Holroyd travelled for three years across Europe. It was in Lausanne in September 1763 that he met the historian Edward Gibbon (1737-1794) who became a life-long friend and confidant. Gibbon wrote: "I have conceived a sincere friendship for Holroyd. He possesses great good sense and honourable sentiments, with a heart the best disposed in the world." When Gibbon died in 1794 he was interred at the Sheffield mausoleum in Fletching church and two years later John Holroyd edited and published the two volume Memoirs of the Life and Writings of Edward Gibbon, Esq.

Throughout his adult life Holroyd was active in politics and wrote extensively on the issues of the day. He entered parliament as M.P. for Coventry in 1780, for Bristol in 1790, and in 1809 he was admited to the Privy Council and Board of Trade, a position he held until his death in 1821

In 1769, John Holroyd purchased Sheffield Park from Lord de La Warr for £31,000. He commenced on extensive changes and developments of the property and its surrounding 120 acres of woodland park. In 1776 he engaged the architect James Wyatt (1746-1813) to enlarge and modernise the 16^th century house in a Gothic style. He also engaged first Lancelot 'Capability' Brown (1716-1783) and then Humphrey Repton (1752-1818) to landscape the gardens.

John Holroyd married in 1767, Abigail Way daughter of Lewis Way and Abigail Lockey, and they had three children, John William, Maria Josepha and Louisa Dorothea. After Abigail's death in 1793, he married, in 1794, Lucy Pelham daughter of Thomas Pelham, 1^st Earl of Chichester, and Anne Frankland. After her death in 1797, he married, in 1798, Ann North the daughter of Frederick North 2^nd Earl of Guilford, and Anne Speke in 1798 and they had two children, George Augustus Frederick Charles (who later became 2^nd Earl of Sheffield) and Anne Frederice Catherine.

Sheffield Park was the principal residence of the Holroyds but they also had property in London at Portland Place where, at the age of 86, he died on 20^th May 1821. His body was interred at Fletching Church in June where the memorial inscription on the decorated screen in the Sheffield mausoleum is immediately above the inscription for his close friend Edward Gibbon