This painting was almost certainly executed to accompany other portraits held by the Deveraux family in the 18th century. Sir Thomas Knollys sister, Lettice married Walter Deveraux, Earl of Essex and 2nd Viscount Hereford in the late 16th century. Given the relative obscurity of the sitter it is quite likely that this portrait is an 18th century version of an earlier Tudor picture that might have existed. Painted by an unknown artist, he has adopted the earlier style of the 16th century most closely associated with Robert Peake. It is more than likely that this is the only known visual representation we have of Sir Thomas.

The sitter was the youngest son of Sir Francis Knollys, (c.1514-1596) statesman to three Tudor monarchs, and Catherine Carey, Chief Lady of the Bedchamber to Elizabeth I. Born sometime around 1555, he was one of nine children brought up at the country estate of Greys Court, Rotherfield Greys in Oxfordshire which had been conferred upon his father by Henry VIII . Not much is known of his early life, but he grew up as the soldier of the family and distinguished himself as a commander in the war in the Low Countries under Maurice, Prince of Orange, later acting as Governor of Ostend in 1586 and prominently aiding Peregrine Bertie (1555-1601) in the Siege of Bergen in 1588. Around this time he married Odelia de Morada, daughter of John Morada, Marquis of Bergen and subsequently had a daughter, Penelope who later married William Le Hunt.

Knollys direct involvement with Bertie means he was at the forefront of the wars in Spanish occupied Netherlands. Bertie, as Earl Willoughby, succeeded Sir Phillip Sidney as Governor of Bergen in 1586. In 1587, Sir John Conway replaced Knollys as Governor of Ostend, probably as a result of Knollys leaving to join Bertie in the struggle with the Spaniards which was to reach a crisis point the following year.

In 1588 Philip of Spain countered the English efforts to destroy his empire in the Low Counties, by sending the infamous Armada to take the war directly to the English throne. The Armada was to collect the army of the Duke of Parma in the Netherlands and ferry it to the English mainland. Bertie was ordered to send back two thousand soldiers for the defence of England and despite a ravaged and depleted force still managed to play an important role in the destruction of the Spanish ships. He firstly captured an enemy man-of-war which ran aground near Ostend and then swiftly closed in on the Duke of Parmas much superior army. Using his small naval force, he threaten the Dukes fleet to such an extent that it could not risk leaving port to assist the now doomed Armada. Later in the year, the Spaniards laid siege to the city of Bergen, but Bertie, with the assistance of Knollys and a small force of troops, held out until the Spaniards withdrew.

Little more is known of Sir Thomas Knollys after this date and according to sources it is believed that he must have died sometime after 1596.

Sources: Burkes Dormant & Extinct Peerage, 1845; Burkes Peerage, 1937; Dictionary of National Biography.