Sir Robert de Crull (or Sir Robert Crull) (1329–1378) was Clerk of the King's Ships (former title 'Keeper and Governor of the King's Ships and Warden of the Sea and Maritime Parts') under Edward III of England, the first English monarch to declare England to be "the Sovereign of the Seas",[1] and during the first year of Richard II's reign.

King Edward had sent him on a mission to Scotland to direct Henry Le Scrop, Ralph de Hastyngs and Roger de Fulthorp to settle the dispute between Henry Percy, 1st Earl of Northumberland and William Douglas, 1st Earl of Douglas respecting the custody of the marches of the Kingdom of England near Scotland.

[2][3] Already in 1367, Henry Percy had been entrusted, as Chief Warden, with the supervision of all castles and fortified places in the Scottish marches.

Edward III had achieved a succession of victories in France enabling him to secure great possessions.

However, after a number of battles well into 1360 the outcome was still in doubt,[7] and Edward was forced to accept the Treaty of Brétigny wherein he renounced his claim to the French throne so that he could secure full sovereignty of the possessions he had in France.

Lionel of Antwerp, Edward's second son, was sent with a force to subdue them which proved to be a failed venture, mainly because these lords had become powerful since England over time had allowed them to be largely autonomous.

John of Gaunt, Edward's third son, conducted the war effort against France, which became disastrous for England.

Crull served as Edward III's Clerk of the King's Ships from 6 October 1359 to the day he died, 22 September 1378 (the first year of Richard II of England)'s reign.

Edward III and his ministers relied on various means to raise money which increased the taxation of his subjects.

[10]: 509  Since the House of Commons of England had the right to grant taxes, it gained political influence; and it was during the reign of Edward III that the foundations were laid for the English brand of constitutional monarchy.

There were also problems with piracy by English crews which led to more than an occasional diplomatic faux pas, such as the men of Southampton burning a friendly Spanish target.

[16] That is why there are numerous accounts of Crull buying supplies for the King's navy, e.g. on 26 February 1366 he bought "... 7000 plus pounds of cables and cords which were paid for in gold English Nobles".