On 21 December 1676, a warrant was passed for "a grant to Charles Beauclerc, the King's natural son, and to the heirs male of his body, of the dignities of Baron of Heddington, co. Oxford, and Earl of Burford in the same county, with remainder to his brother, James Beauclerc, and the heirs male of his body." A few weeks later, James was given "the title of Lord Beauclerc, with the place and precedence of the eldest son of an earl." Just after the death of Henry Jermyn, 1st Earl of St Albans at the turn of the year, on 5 January 1684, King Charles granted his son Charles, Earl of Burford, the title of Duke of St Albans, gave him an allowance of £1,000 a year, and granted him the offices of Chief Ranger of Enfield Chace and Master of the Hawks in reversion (i. e. after the death of the current incumbents). He became colonel in the 8th regiment of horse in 1687, and served with the emperor Leopold I, being present at the siege of Belgrade in 1688.
When his mother died (14 November 1687), Beauclerk received a large estate, including Burford House, near Windsor Castle. After the Battle of Landen in 1693, William III made Beauclerk captain of the gentlemen pensioners, and four years later gentleman of the bedchamber. His father had given him the reversion of the office of Hereditary Master Falconer and that of Hereditary Registrar of the Court of Chancery, which fell vacant in 1698. His Whig sentiments prevented his advancement under Queen Anne, but he was restored to favour at the accession of King George I. In 1718, George made him a Knight of the Garter.
On 17 April 1694 he married Lady Diana de Vere, daughter and heiress of Aubrey de Vere, 20th and last Earl of Oxford. She was a well-known beauty, who became lady of the bedchamber to Caroline of Ansbach, Princess of Wales. The couple had twelve children;
Several legends describe how Beauclerk became Earl of Burford. The first is that on arrival of the King, his mother said, "Come here, you little bastard, and greet your father." When the king rebuked her for calling him that, she replied, "Your Majesty has given me no other name to call him by." In response, Charles created him Earl of Burford.
Another legend is that Beauclerk's mother held him out of a window (or above a river) and threatened to drop him unless he was given a peerage. Charles supposedly cried out "God save the Earl of Burford!" and subsequently created that peerage.