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Marymount International School London

🇬🇧 London · Founded 1955 · IB · Ages 11-18

An intimate, all-girls Catholic IB school with a deep international identity and an ISI 'Excellent' track record.

Curricula

IB

Age range

11-18

Languages of instruction

English

Annual fees

SGD Day GBP 39,540/yr; full boarding GBP 66,990/yr (2026-27, incl. VAT)

Enrollment

250

Boarding

Yes

IB authorised

MYP, DP

Independent Schools Inspectorate (ISI) 2022

Excellent

Accreditations

Council of International Schools (CIS), Middle States Association of Colleges and Schools, International Baccalaureate Organisation (IBO)

Tier Profile

We only tier dimensions backed by a public inspection verdict or verifiable accreditation. Other dimensions show a data flag — never a guessed score.

Inspection & Accreditation 🟢S — Exceptional

How we score →

Independent assessment — BrightKey takes no payments or commission from this school. Ratings use verified public data only. Why this matters →

BrightKey's Assessment

Marymount International School London is an independent Catholic day and boarding school for girls aged 11 to 18, founded in 1955 by the Religious of the Sacred Heart of Mary on a leafy campus in Kingston upon Thames. It is one of the pioneers of the International Baccalaureate in England — adopting the IB as its main curriculum in 1979 — and today runs the IB Middle Years Programme in the lower school and the IB Diploma Programme in the Sixth Form. It does not offer the IB Primary Years Programme, so the school is a secondary-and-sixth-form institution rather than a full PYP-to-DP continuum.

The school is small and deliberately so, with roughly 250 students drawn from dozens of nationalities, which gives it an unusually high adult-to-student ratio and a genuinely global classroom. Around a quarter of students board, and the school is a member of the Boarding Schools Association and the Girls' Schools Association. Its Catholic, RSHM-rooted ethos and connection to the worldwide Marymount network shape a values-led, pastoral environment.

Academically it punches well above its size. The Class of 2025 posted a 37-point average IB Diploma score against a global average near 30, a 100% pass rate, and 38% of candidates scoring 38 points or higher — placing it among the stronger IB cohorts internationally. Roughly a third of graduates earn a bilingual diploma, reflecting the multilingual student body.

Oversight is robust: the school is accredited by the Council of International Schools and the Middle States Association, is an authorised IB World School, and is inspected in England by the Independent Schools Inspectorate. Its November 2022 ISI Educational Quality inspection returned an 'Excellent' outcome, with a subsequent routine inspection in October 2025.

Why These Ratings?

Inspection & AccreditationS — Exceptional

Tiered 'S' on the strength of the verbatim 'Excellent' outcome from the November 2022 ISI Educational Quality Inspection, reinforced by triple accreditation (CIS, Middle States, IBO) and a follow-up ISI routine inspection in October 2025.

Strengths & Trade-offs

Strengths

  • ISI 'Excellent' Educational Quality outcome (2022) plus CIS, Middle States and IBO accreditation
  • Pioneer IB credentials — adopted the IB as its main curriculum in 1979, among the first in England
  • Strong, consistent IB Diploma outcomes (37-point average, 100% pass rate, Class of 2025)
  • Small ~250-student, multi-nationality community giving high individual attention
  • Established girls' boarding option within a values-led Catholic RSHM ethos

Trade-offs

  • No IB Primary Years Programme — provision starts at age 11, so no early-years or primary pathway
  • Very small enrolment limits breadth of co-curricular and peer cohort scale
  • Premium fees (GBP 39,540 day / up to GBP 66,990 full boarding for 2026-27)
  • Single-curriculum (IB only) with no A-level or alternative-pathway fallback

Is It Right For You?

Best For

  • ✓Families seeking an all-girls, values-led Catholic education
  • ✓Internationally mobile families wanting a recognised full IB Diploma pathway
  • ✓Students aged 11+ who thrive in a small, close-knit cohort
  • ✓Families needing girls' boarding (full, weekly or flexi) near London

Not Ideal For

  • ✕Families needing early-years or primary provision (none below age 11)
  • ✕Boys, or families wanting a co-educational setting
  • ✕Students wanting A-levels or a non-IB curriculum
  • ✕Budget-sensitive families given the premium fee level

Curriculum

A full-IB school: the IB Middle Years Programme in the lower school (ages ~11-16) and the IB Diploma Programme in the Sixth Form. The school adopted the IB as its main curriculum in 1979, among the earliest in England. It does not offer the IB Primary Years Programme or A-levels.

What is the IB? →

Fees

For 2026-27 (inclusive of VAT): day tuition GBP 39,540 per year; weekly boarding GBP 64,110 total; full boarding GBP 66,990 total. Flexi-boarding is available from one night per week, with a 10% sibling discount for a younger daughter when sisters attend together. A single tuition figure applies across year groups.

Admissions

Entry is for girls from age 11 via the school's own assessment process; an application fee and acceptance fee apply, with a refundable deposit for boarders. Around a quarter of students board.

Campus Life

Set on George Road in Kingston upon Thames, the school combines a Catholic RSHM ethos with a deliberately small, multi-nationality community of about 250 girls representing dozens of countries. It is part of the worldwide Marymount network, offers full, weekly and flexi-boarding, and is a member of the Boarding Schools Association, Girls' Schools Association and International Coalition of Girls' Schools.

University Placement

School-reported · not independently verified

School-reported, unverified: graduates are described as progressing to top-tier universities worldwide, with around a third earning a bilingual IB diploma (Class of 2025).

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Compare Marymount International School London with

Side-by-side: curriculum, fees, accreditation, honest trade-offs

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Also in London

The American School in LondonACS International Schools (Cobham, Egham & Hillingdon)TASIS The American School in EnglandSouthbank International SchoolInternational School of London (ISL London)

Questions parents ask

Is IB or A-Levels better for UK university admissions? →What's the best school curriculum for a child who might move countries? →Which are the best IB schools in Singapore for international families? →When should an internationally-mobile family start the university application process? →
The IB Diploma ProgrammeA-LevelsIGCSE
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