Aylesbury Grammar School (AGS) is one of Buckinghamshire’s most sought-after boys’ grammar schools. It was founded in 1598, is rated Outstanding by Ofsted and produces some of the strongest GCSE results in the county, and it draws applications from families across Aylesbury and well beyond. Competition for its 186 Year 7 places is intense, and a place is never guaranteed simply by passing the entrance test.
This guide explains what it takes to get into AGS: how the Buckinghamshire Secondary Transfer Test works, what score you should realistically aim for, why catchment matters so much here, and how to prepare so your son walks into the exam confident. If you are planning ahead for the September 2027 intake, the most important dates and decisions are set out below.
School overview
Aylesbury Grammar School is a selective boys’ school for ages 11–18, founded in 1598 by Sir Henry Lee of Ditchley. It sits on Walton Road in central Aylesbury (HP21 7RP) and has a close relationship with Aylesbury High School, the partner girls’ grammar, including a sibling cross-priority that we cover later.
The school’s quality is well documented. At its most recent inspection (2 November 2022), Ofsted graded AGS Outstanding overall and Outstanding in every category, the highest possible judgement.
The GCSE outcomes back this up. According to the Department for Education’s published 2024/25 performance data, AGS recorded an Attainment 8 score of 74.5, with 95.2% of pupils achieving grade 5 or above in both English and maths, and an EBacc average point score of 6.92. (A Progress 8 measure was not calculated for 2024/25, as there was no Key Stage 2 baseline for the cohort.) The school also has a strong sixth form, although headline A-level statistics are not published in a form we can verify from a primary source, so we focus here on the GCSE picture.
The entrance exam: Buckinghamshire Secondary Transfer Test
Entry to AGS is by the Buckinghamshire Secondary Transfer Test (STT), the county-wide 11-plus administered by GL Assessment. Every boy applying for a Year 7 place must sit it.
The STT consists of two papers of roughly 60 minutes each, covering three areas:
- Verbal reasoning: working with words, language and logic
- Non-verbal reasoning: spotting patterns and relationships in shapes and diagrams
- Mathematics: number, arithmetic and problem solving
The papers are taken on consecutive testing days. Pupils at Buckinghamshire state primary schools are normally entered automatically. Children at independent schools or schools outside the county must be registered actively by their parents.
Pass mark and realistic score targets
The qualifying score for the Buckinghamshire STT is 121. A boy who reaches this standardised mark is deemed to have qualified for a grammar school place.
The key point at AGS is that qualifying is the start, not the finish. Because the school is heavily oversubscribed, simply scoring 121 does not secure a place. When more qualified boys apply than there are seats, the school’s admissions criteria decide who is offered a place, not the test score. So while 121 is the threshold, we encourage families to aim comfortably above it. A confident margin protects against a difficult exam day and reflects the genuine standard of the competition.
It is equally important to understand that at AGS, catchment matters enormously. A high score from outside the catchment area is no substitute for living within it. We explain why in the next section.
Key dates for September 2027 entry
For boys hoping to start at AGS in September 2027, the timeline is:
- Registration deadline: 21 June 2026
- Test dates: 8 and 10 September 2026
Miss the registration window and your son cannot sit the test for that cycle, so diarise it early. AGS also runs an open evening for prospective families (a session for Year 4 and 5 parents was scheduled for Monday 6 July 2026). Check the school’s website for the latest event dates.
Competition and catchment
AGS admits 186 boys into Year 7 (the published admission number in the September 2027 determined policy). With far more qualified applicants than places, the school is a catchment-area grammar, and its oversubscription criteria are applied in a strict order.
According to the Admissions Policy 2027 (determined 5 December 2025), qualified boys are offered places in this priority order:
- Looked-after and previously looked-after children
- Up to 6 Pupil-Premium boys scoring 115–120
- Catchment Pupil-Premium boys
- Siblings of current AGS boys
- Siblings of current Aylesbury High School girls
- Siblings of former AGS boys
- Children of qualified members of staff
- Boys with exceptional medical or social need
- Other boys living in the catchment area
- All other qualified boys
The pattern is clear: after the priority categories, catchment boys are offered places before boys living outside the catchment. Where a tie-breaker is needed, distance is measured to the main gate on Walton Road, with closer homes prioritised.
Two practical lessons follow. First, families inside the catchment have a significant advantage, and those nearer the school have the edge in any tie-break. Second, the sibling cross-priority with Aylesbury High School is a real factor: a boy with a sister at Aylesbury High ranks above a catchment boy with no sibling link. If you have daughters at, or heading to, Aylesbury High, that connection can strengthen your son’s position.
Because catchment is so decisive here, check your address against the school’s catchment area before pinning your hopes on AGS, and consider it alongside other Buckinghamshire grammars when you list preferences.
Preparation timeline and strategy
The boys who do best are rarely the ones who cram in the final months. They are the ones who built genuine reasoning skill steadily over time.
Start in Year 4. This is the ideal point to begin. It gives roughly eighteen months to develop verbal reasoning, non-verbal reasoning and maths without pressure, and to turn unfamiliar question types into second nature well before the September test.
Treat the subjects separately. Verbal reasoning, non-verbal reasoning and maths each demand different skills (and English underpins verbal reasoning), so they deserve dedicated attention rather than a single generic “11-plus” approach. A boy can be strong in maths yet thrown by non-verbal patterns, and working on each strand individually closes those gaps.
Use mocks under timed conditions. Full mock tests build exam stamina, surface weak areas and remove the shock of the clock. Pacing across two roughly 60-minute papers is itself a skill that only sitting realistic mocks can teach.
At Think Smart Academy, our 11-plus classes are capped at 8 pupils so every child gets real attention rather than getting lost in a crowd. We start every family with a free diagnostic assessment to pinpoint where your son stands across all four areas, so preparation is targeted from day one. We teach from our High Wycombe centre and online, so families across Buckinghamshire, including those around Aylesbury, can access the same structured programme.
Common mistakes to avoid
- Treating 121 as the finish line. It is the qualifying mark, not a guaranteed offer. At an oversubscribed school like AGS, aim higher.
- Ignoring catchment. A brilliant score from outside the catchment can still lose out to a qualified boy who lives nearby. Know where you stand before you commit.
- Leaving registration too late. Miss 21 June 2026 for the 2027 cycle and there is no place to sit the test.
- Cramming late. Reasoning skill compounds. Starting in Year 6 leaves too little time to build it properly.
- Neglecting the weakest subject. Most boys have one area that drags the average down. Diagnose it early and work on it specifically.
- Skipping timed mocks. Knowing the content is not the same as performing under the clock across two papers.
Next step
Getting your son into Aylesbury Grammar School comes down to two things: a strong, confident test score and a clear understanding of the catchment and sibling rules that decide who is offered a place.
We can help with the first and advise on the second. Read our full breakdown on the Aylesbury Grammar School page, then book a free consultation to claim your son’s diagnostic assessment and map out a preparation plan built around the September 2027 timeline.