ACS International Schools vs Marymount International School London
🇬🇧 London · Side-by-side comparison on verifiable public data.
Both carry a public inspection verdict: ACS International Schools is Independent Schools Inspectorate (ISI) "Met all standards (2025 EQI, post-2023 framework)" and Marymount International School London is Independent Schools Inspectorate (ISI) "Excellent" — a rare pairing where an official quality rating can be compared head-to-head. On cost, ACS International Schools has the noticeably lower entry fee — a material difference for budget-conscious families. See the table below for the figures, and verify against each school's own published fees.
Key Facts
| ACS International Schools | Marymount International School London | |
|---|---|---|
| Curriculum | American / IB | IB |
| Ages | 2-18 (Cobham); 3-18 (Egham, Hillingdon) | 11-18 |
| Languages of instruction | English | English |
| Annual fees | ACS Cobham 2026-2027 day tuition GBP 9,950-39,960/yr; 7-day boarding (Grades 8-12) up to GBP 69,060/yr inclusive | Day GBP 39,540/yr; full boarding GBP 66,990/yr (2026-27, incl. VAT) |
| Enrollment | 2,200 | 250 |
| Boarding | Yes | Yes |
| Inspection rating | Independent Schools Inspectorate (ISI): Met all standards (2025 EQI, post-2023 framework) | Independent Schools Inspectorate (ISI): Excellent |
| Accreditations | New England Association of Schools and Colleges (NEASC), College Board, International Baccalaureate Organization, Educational Collaborative for International Schools (ECIS), Independent Schools Association (ISA) | Council of International Schools (CIS), Middle States Association of Colleges and Schools, International Baccalaureate Organisation (IBO) |
Strengths
- ✓Dual American (High School Diploma plus AP) and IB pathways under one operator, rare in the London market
- ✓ACS Egham offers all four IB programmes (PYP, MYP, DP, CP) - a full through-IB continuum
- ✓Highly international community of 70+ nationalities with structured EAL and home-language support
- ✓Long-established (since 1967) with NEASC accreditation and College Board / IB partnerships
- ✓Boarding available at Cobham (Grades 8-12), including flexible temporary boarding options
- ✓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
- !Premium fees, with senior-year day tuition near GBP 40,000 and full boarding around GBP 69,000 a year at Cobham
- !IB continuum breadth (all four programmes) is concentrated at Egham, not uniform across all three campuses
- !IGCSE is not offered, so families wanting a British GCSE route are not served
- !Current ISI framework yields a 'met all standards' outcome rather than a published top graded band
- !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
Best Fit For
- • Internationally mobile families wanting a US diploma plus AP and/or IB pathway
- • Students targeting US university applications who value AP and a transcript-based diploma
- • Families needing boarding within commuting distance of London (Cobham)
- • Children needing EAL support within a multinational peer group
- • 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
University Placement
School-reported · not independently verified
School-reported, unverified: ACS promotes US and international university destinations across its alumni, but no independently verified placement figures were found.
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).
More Comparisons
Frequently Asked Questions
Should I choose ACS International Schools or Marymount International School London?
ACS International Schools is best for: Internationally mobile families wanting a US diploma plus AP and/or IB pathway. Marymount International School London is best for: Families seeking an all-girls, values-led Catholic education. The right choice depends on target curriculum, budget, and family priorities — the two are not linearly comparable.
How do fees compare between ACS International Schools and Marymount International School London?
ACS International Schools: ACS Cobham 2026-2027 day tuition GBP 9,950-39,960/yr; 7-day boarding (Grades 8-12) up to GBP 69,060/yr inclusive. Marymount International School London: Day GBP 39,540/yr; full boarding GBP 66,990/yr (2026-27, incl. VAT). Verify against each school's own published fees; some figures are sourced from third-party aggregators.
What curricula do ACS International Schools and Marymount International School London offer?
ACS International Schools: American, IB. Marymount International School London: IB. ACS International Schools inspection: Independent Schools Inspectorate (ISI) "Met all standards (2025 EQI, post-2023 framework)". Marymount International School London inspection: Independent Schools Inspectorate (ISI) "Excellent".
Do ACS International Schools or Marymount International School London offer boarding?
ACS International Schools: offers boarding. Marymount International School London: offers boarding.
Questions parents ask
This comparison is BrightKey's independent assessment using verifiable public data only. University-placement figures are school-reported and not independently verified. BrightKey takes no payments from schools. Our method →