Grantham Grammar School, also known as The King's School, has an unbroken history on the same site from its endowment as one of the last acts of Bishop Richard Fox in 1528. Fox was a local boy who rose due to his position as secretary to Henry, Duke of Richmond, while in exile in France prior to the famous events of the battle of Bosworth that led to Henry's capturing the throne as Henry VII. Ultimately Bishop of Winchester, Fox also founded Taunton Grammar School.

The heyday for King's probably came in the 17th century, with alumni including the 'Cambridge Platonist', Henry More, Poet Laureate Colley Cibber, and the outstanding Sir Isaac Newton, not to mention successful 18th C. mathematician, John Newcome. Previously the most notable old boy had been William Cecil, Lord Burleigh, whose family seat survives in the grand Burleigh House near Stamford in Lincolnshire. Burleigh became Principal Secretary to Queen Elizabeth I. Newton meanwhile, as was customary in his time, carved his signature on the wall of what is today's functioning school library. Visitors from around the world have come and viewed this landmark evidence of Newton's education.

A small school of perhaps a few dozen scholars at this period, it remained less than one hundred strong until the 20th century, and its reputation did not grow as other similar schools grew and outpaced it. The most notable recent pupil would probably be J.W. Wand, Bishop of London from 1945 to 1956. Now a school of over 800, it unusually remains a selective boys' state grammar school, as it has always been, and despite modern development on the town centre site, retains many buildings dating from Newton's era and before.