Following the death of Ben Jonson in 1637, Davenant was named Poet Laureate in 1638.  He was a supporter of King Charles I in the English Civil War. In 1641, before the war began, he was declared guilty of high treason by parliament along with John Suckling, after he participated in the First Army Plot, a Royalist plan to use the army to occupy London. He fled to France. Returning to join the king's army when the war started, he was knighted two years later by king Charles following the siege of Gloucester. In 1645, after the Royalist defeat at the Battle of Naseby, he retired to Paris, where he became a Roman Catholic and worked on his epic poem Gondibert. That same year he was appointed Emissary to France, and in 1649 was given the symbolic post of treasurer of the colony of Virginia by the exiled Charles II. The following year, he was made lieutenant governor of Maryland, but was captured at sea, imprisoned, and sentenced to death. He is said to have been saved by the intervention of John Milton. He spent all of 1651 in the Tower of London, where he continued writing Gondibert. On his release in 1652, he immediately published Gondibert, but he was only pardoned in 1654. In order to avoid the strict laws of censorship in force in all public places at the time, he turned a room of his home, Rutland House, into a private theatre where his works, and those of other writers considered seditious, could be performed. A performance of his The Siege of Rhodes at Rutland House in 1656 is considered to be the first performance of an English opera, and also included England's first known professional actress, Mrs Coleman.
Question: How many years after being Poet Laureate was Davenant declared guilty of high treason by parliament?
Answer: 4