St Mary's Independent School, formerly named St Mary's College, was an independent day school for boys and girls in Southampton, Hampshire, England.

The school was located on the site of a former a country house called Bitterne Grove, built c1790 by Richard Leversuch. In 1910 it was bought by the French order of the Brothers of Christian Instruction and renamed as St Mary's House. Initially it was a centre for students who were exiled from France due to anti-clerical laws passed there in 1903 and training for the Brotherhood, until the centre was relocated to Highlands College, Jersey, in the Channel Islands.

In 1922 it became the first Secondary School for Catholic boys in Southampton, under the name of St Mary's College, and opened with five Brothers and 30 pupils.^[1] During the Second World War rapid expansion of the school took place; the number of pupils passing from 200 at the start of the War to 400 at the end.^{[citation needed]} In 1992 the junior department started taking girls and in 2000 the senior department was opened to girls, and latterly approximately 25% of the pupils were girls.^{[citation needed]} Former pupils are known as Old Simmarians.^[2]

From 1925 to 1964 Rev Brother Maurice worked at the school.^[3] Before WWI he had been sent as a teacher amongst the Blackfoot Indians in Montana and Eskimos on the Yukon River. During the war he served with great distinction in the French Medical Corps. He was twice wounded and also mentioned three times in dispatches for gallantry. He was awarded the Croix de Guerre with palm and two stars, as well as the Médaille Militaire and, for his bravery on the battlefield of Verdun in 1916, the Legion of Honour Military Medal. He was twice headmaster of St Mary's (1928–31 and 1937–43) and later head of its prep-school, Charlton.^{[citation needed]}

In 2013 Ofsted judged the school as 'Good'.^[4] In 2018 another inspection judged it to 'Requires Improvement'.^[5] In 2019 it was reinspected and judged 'Inadequate'.^[6]

In 2020 the school went into administration following financial difficulties which had been "significantly impacted" due to the coronavirus pandemic.^[7] The school was acquired and refurbished by private investors and re-opened in Sept 2021 as a school for children aged 7–16 with social, emotional and mental health needs, under the new name of Yarrow Heights School.^[8]

This article's list of alumni may not follow Wikipedia's verifiability policy. (June 2020)

• Roy Brindley, poker player, TV commentator, author^{[citation needed]}
• Robert Chote, Chairman of the Office of Budget Responsibility^{[citation needed]}
• Prof. Anthony R. Dickinson, Professor of Neuropharmacology, UCL^{[citation needed]}
• Patrick Garland, writer, actor, theatre and film director^[9]
• Philip Hoare, writer, TV programme maker, journalist, Professor of Creative Writing at Southampton University^{[citation needed]}
• Nick Holmes, former Southampton footballer, FA Cup winning team^{[citation needed]}
• Richard May, a speedway rider who rode for Reading Racers and Poole Pirates between 1969 and 1977^{[citation needed]}
• Andrew Surman, former Southampton and current Norwich City footballer^{[citation needed]}
• John Sydenham, former Southampton footballer^{[citation needed]}
• Sir Gerry Whent, CEO of Vodafone^[10]
• Richard George Deverell: became Director of the Royal Botanic Gardens, Kew in September 2012. He was previously Controller of CBBC

• History of Bitterne Grove, with photos
• School Website - with archive images
• St Mary's College at Good Schools Guide