The precise date of the establishment of the Inn in the premises of the Greys' manor house is not documented. The earliest known reference to the existence of the Inn as a lodging of lawyers appears to be in 1370, when it is referred to as a "hospitium".

William Walsingham (b. after 1480, d. 1534) was a lawyer and landowner.

William Cecil, later Lord Burghley (1520-1598), admitted 1541 and elected an Ancient 1547.

Defeat of the Spanish Armada led by the Admiral Lord Howard of Effingham, a member of the Inn.

On 28 December 1594 the first known performance of Shakespeare's "The Comedy of Errors" took place in Gray's Inn Hall, as part of the Inn's Christmas festivities.

Around 1595-1600 the Inn ceased to use the arms of the de Grey family and instead adopted the griffin as its official badge.

The Inn’s gardens, known as ‘the Walks’, were laid out by Sir Francis Bacon in 1608.

Of the 47 scholars involved with work on the King James's Bible, 8 were connected to the Inn.

Members John Bradshaw (1602-59; called 1627) and John Cooke or Cook (1608-60; called 1631) were the judge - President of the High Court of Justice - and prosecutor respectively at the trial of Charles I in 1649.