The college was founded in 1879 as South Eastern College. The name was changed in September 1906 because of the association with the Railway network to St Lawrence College by its location in the St Lawrence area of Ramsgate. New colours were also given: maroon and white. The school rapidly outgrew the single house, leading to the main building of the present day college by 1884. The chapel was completed in 1927. During the world wars, the school was evacuated to Chester and Courteenhall in Northamptonshire, seat of Sir Herewood Wake, because of its position on the South-East coast. Later in the school's existence, girls were admitted, and the current mix of sexes is now roughly equal. There were initially 4 houses:- Light Red, Dark Red, Light Blue and Dark Blue. These became Grange, Tower, Manor and Lodge. During World War II a fifth house was added called Courtenay when a nearby school having failed to maintain numbers was incorporated into the school. Newlands was later added for day scholars and Deacon followed as the Junior end of this house. In 1930, Richard Maunsell designed for the Southern Railway a fleet of 40 "Schools Class" locomotives one of which was named St Lawrence. These locos were compact but particularly powerful, weighing over 100 tons with tender. As late as 1958 the St Lawrence Loco was attached to the School Train departing from Ramsgate. Parts of the tender still exist on the Bluebell Railway.
The Senior School is divided into five separate houses. The oldest, Tower and Lodge, the two boy's boarding houses, were created in 1889. Newlands is the boys' day house, while Laing is the girls' day house. Boarding girls are part of Bellerby. All houses are located in the main school building except Bellerby, who have their own building which is situated in the site of the previous Taylor Hall. Cameron and Courtenay are mixed boarding and day sub-houses, respectively, for the Middle School. They accommodate students from age 11 to 13. They are housed in the modern Kirby House Building, which opened in January 2007 by the Archbishop of Canterbury, Rowan Williams. In January 2013, Mark Aitken retired his post of Headmaster and was succeeded by Antony Spencer.
Junior school
St Lawrence College Junior School is located on the same site as the Middle and Senior schools and accommodates pupils from age 3 to 11. The Junior School pupils study in the Hamblen Block which includes classrooms for Years 3-6.
Performance
In 2009, the Daily Telegraph placed the school 330 in its League Table of Independent SchoolA-level results, with 48.81% of pupils gaining A or B grades at A-level. In 2012, the school gained a pass rate of 92.9% with 18% of them being at grades of A and A* at A-level. The GCSE results had a pass rate of 86.5% and 15.5% being at grades of A*. In 2017, the school had 30% A*/A grades at A-level, and 33% A*/A at GCSE, despite the introduction of the new exams.
