Daniel Blagrave was the fifth son of the clothier and chess-master, Alexander Blagrave of Reading and his wife, Margaret. His younger brother was Joseph Blagrave, the Astrologer. The family lived at Southcote Lodge, on the Southcote House estate of Alexander's brother, the famous mathematician, John Blagrave. When Daniel was eight, the family inherited the lease on Southcote House from his uncle, but his father died the following year. Presumably he brought up by his mother under the watchful eye of another uncle, Edward Blagrave. He eventually - at the age of thirty-four - gained a legal education at the Inner Temple in London, but initially made his way in the administration of his home town of Reading.

Daniel sat in Parliament for the Borough, from 3rd November 1640 and, at the outbreak of the Civil War, allowed the Earl of Essex to use Southcote House as the Roundhead headquarters during the Siege of Reading in April 1643. It's not clear where his elder brother or the rest of the family were at the time. After the town fell to Parliament, he  was appointed Assistant (1644) and then Recorder of the Corporation (1645), as well as Treasurer of the County Committee. After he was called to the Bar in 1648, he spread his net still wider. He was dismissed as recorder in 1656, but reinstated in 1658.

Daniel became prominent in the Rump Parliament of 1648 and was a friend to independent MPs. He was involved in the preparations for the trial of King Charles I and attended the High Court of Justice throughout the proceedings. Finally, he became one of the commissioners to sign the King's death-warrant and he was executed in January 1649. This was followed up with involvement in the abolition of the House of Lords. He was keen to gain appoints on committees and commissions and wrote frequently to Elias Ashmole for astrological predictions about his career. In July 1651, he was appointed Commissioner for Forfeited Estates, sequestering delinquents and selling confiscated and church lands. He was appointed by the Parliament to the office of exigenter of the Court of Common Pleas, said to have been worth £500 per annum, and also became a Master in Chancery. He was also Parliamentary Treasurer for the county of Berkshire and, in 1654, was named one of the commissioners for the ejection of scandalous and inefficient ministers, in which capacity he was accused by his enemies of using undue severity and of proving a vexatious persecutor of the clergy. By the means, which he had acquired from his different offices, he was able to purchase the fee-farm rent of the manor of Sonning, in Berkshire, and other estates, as it is said, on easy terms. He sat in the Convention parliament of 1658; but, upon the Restoration, he fled the Kingdom and settled at Aachen, where he died in 1668. By his wife, Elizabeth Hull, daughter of the London merchant Abraham Hull,  he left a large family of eight sons and three daughters, including his eldest son, Charles Blagrave, who inherited his Jamaican estate at Cardiff Hall in St. Ann's, and the St. Paul's Churchyard publisher and bookseller, Obadiah Blagrave. 

Edited from Leslie Stephen's 'Dictionary of National Biography' (1886).