Little is known of Broxbournebury before the Norman Conquest, but records show that in 1168 the manor was granted by Robert de Beaumont, Earl of Leicester, to the Knights Hospitallers of St John of Jerusalem, who continued to hold it until their order was suppressed by King Henry VIII in 1553. It was granted in 1554 to the sheriff of Hertfordshire and Essex, John Cock, who had been acting as bailiff of the estate. He died in 1557, and his son who succeeded him was appointed Keeper of the Ward- robe to Queen Elisabeth, by whom he was later knighted; he also held his appointment after the accession of King James I.
In 1603, following the death of Queen Elizabeth, when James was travelling south to claim the crown, he came here to Broxbournebury on 6 May and was sumptuously lodged and entertained by Henry Cock, continuing his journey to London on the following day. This Henry Cock died in 1609 and was buried in Broxbourne Church where a fine monument was erected to him and his wife at the east end of the south wall of the chancel. He had built himself a substantial house in his park at Broxbournebury – it was doubtless timber-built and plastered – and some of the brick- work of this building and some of the window mullions may still be seen.

William Shakespeare

It is unlikely that anything remains of the house of the Knights of Jerusalem.
Both the county historians, Chauncy and Salmon, state that they had a hospital at Broxbourne, which probably stood either on the site of the present building or somewhere close by in the park.

On the death of Sir Henry Cock the estate went to his daughter Elizabeth, wife of Sir Richard Lucy, Bart, who survived his wife, who died in 1645, by over twenty years. It was Sir Richard Lucy who founded the boys’ school at Broxbourne by his will, dated 1667, giving £20 per annum to be paid for ever, in the nature of a rent charge out of his estates in Hampshire, for ‘Erecting and maintaining a Free School at Broxbourne, for teaching the poor children at Broxbourne to read and write English’. Sir Richard had only a life interest in the estate, so at his death in 1667 it passed to Sir John Monson through his marriage to Ursula, grand-daughter of Sir Henry Cock. It was in the park of the Lucy family at Charlcote that Shakespeare was supposed to have stolen deer, and was prosecuted by the owner, Sir Thomas Lucy. Shakespeare retaliated with a ballad which so incensed Sir Thomas that he hounded him out of Warwickshire. Much doubt has been cast upon this story which is probably true in essence, if not in detail. It is probable that Justice Shallow in The Merry Wives of Windsor is a caricature of Sir Thomas Lucy.