What this guide covers on the hill
This page covers Harrow on the Hill only, meaning the Village, Harrow School, and Roxborough Park and The Grove conservation areas, which together make up a study area of about 55.6 hectares in the London Borough of Harrow. Streets and suburbs beyond those three boundaries are outside its scope.
For the borough beyond these designations, the Harrow guide is the place to look. Everything here comes from public datasets and describes the hill as a group of conservation areas, never any one house, school building or garden.
Records for the hill's conservation areas
Every statement below links to the public record it comes from; sources were re-checked on .
Boundaries and council documents
On planning.data.gov.uk the Village conservation area is mapped at about 20.6 hectares, Harrow School at about 16.7 hectares and Roxborough Park and The Grove at about 18.3 hectares, without a designation date for any of them.
Harrow Council's page for the hill's conservation areas and its supplementary planning document for the hill are read first when changes are proposed.
Separate character appraisals are published for the Village, Harrow School and Roxborough Park areas.
Nothing for the hill turns up in the Article 4 records collected on planning.data.gov.uk; an absence there can simply reflect incomplete loading, so Harrow Council is asked about directions before any reliance on householder permitted development.
Listed buildings
Sixty-two list entries fall inside the three boundaries in the list-entry points published for the National Heritage List, queried on 1 November 2026: 2 at Grade I, 4 at Grade II* and 56 at Grade II.
Grade I applies to the Parish Church of St Mary and to The Old Schools, Harrow School.
At Grade II* the list names the Harrow School Chapel, the school's Speech Room and Vaughan Library, and the Harrow School War Memorial Building, Memorial Shrine, Ceremonial Staircase and Retaining Wall.
Five of those six higher-graded entries are Harrow School entries, and since a single entry can cover a group or a boundary wall, the record for each address is consulted rather than inferred from its neighbours.
A registered park
Harrow Park, formerly Flambards, a Grade II registered park and garden, overlaps about 2.17 hectares of the study area.
Planning decisions give weight to a registered landscape even though no extra consent regime attaches to it, so for houses close to Harrow Park the Historic England register entry is relevant to garden buildings and boundary works.
Ground on the hill
Of five sample points, the BGS geology viewer at 1:50,000 places three on the Claygate Member, one on London Clay Formation and one on Bagshot Formation sand, with no superficial deposits mapped at any point.
That mix matters: sand drains freely and can be washed out by leaking drains, while clay-bearing beds such as the Claygate Member and London Clay shrink and swell with moisture and tree roots, so the mapped units are read alongside what the inspection finds.
Where sand lies over clayey strata, water can gather at the junction, so on a sloping plot the retaining walls, stepped gardens and drainage outfalls are examined with the BGS mapping as a guide to which units are present.
Flood mapping
The Environment Agency's Flood Map for Planning shows no part of the three conservation areas in Flood Zone 2 or 3.
That map leaves defences out and does not assess single properties, and run-off on a slope is a separate question, so the national long-term flood risk record, which includes surface water, is consulted for the address.
Housing in the surrounding LSOAs
Two surrounding statistical areas, LSOAs E01002137 and E01002129, contain about 2,450 dwellings in the VOA's Council Tax stock of properties for 2025, where every count is rounded to the nearest 10.
The age profile is split: the VOA build-period table dates 48.6% of dwellings to 2000 or later and 20.4% to before 1900, with 9.8% in 1973-1999, 8.6% in 1900-1918, 6.5% in 1945-1972 and 4.9% in 1919-1939.
Flats or maisonettes make up 77.6% of those dwellings in the type figures, with terraced houses at 11.8%, semi-detached at 6.9% and detached at 3.3%.
Only 12.7% sit in bands F to H in the VOA band counts, while band C is the largest at 40.8%.
The two are surrounding LSOAs, not the hill's designations, and the large post-2000 share in the VOA data is a reminder that these counts describe the surroundings, not the historic core.
Instruction pages for the hill
Pages in the first list deal with one instruction type for addresses on the hill; the second list links the firm's general service pages.
Other guides in the borough and beyond
Most of the borough, including the town around the hill, is covered by the Harrow guide. The Pinner page covers three of that area's conservation areas, and guides for Wembley and Willesden complete the nearby set.
Harrow on the Hill property questions
Which of the three conservation areas covers my address?
Check the mapped lines for the Village, Harrow School and Roxborough Park and The Grove areas on planning.data.gov.uk. Together they cover about 55.6 hectares; an address on a boundary road should be checked against the exact line, not a postcode.
How many list entries are on the hill?
The National Heritage List data returns 62 inside the three boundaries, queried 1 November 2026: 2 Grade I, 4 Grade II* and 56 Grade II. A list entry is a record rather than a building count, and one entry can take in several structures.
Is the ground on the hill clay or sand?
Both appear. The BGS map shows Claygate Member at three of five points, Bagshot sand at one and London Clay at one. Sand drains freely but can be washed out by leaks, and clay-bearing beds move with moisture; the map is not site-specific.
Is the hill exposed to river flooding?
None of the three conservation areas is in Flood Zone 2 or 3. Surface water is mapped separately by the long-term risk service run on GOV.UK, and on sloping ground run-off and drainage capacity still deserve a check at the property.
Why do the housing figures show so many new flats?
The figures come from two surrounding LSOAs rather than the conservation areas, and the VOA 2025 figures date 48.6% of their dwellings to 2000 or later and record 77.6% as flats. That describes the surroundings, so the age of a home inside the designations is established individually.
What should owners near the school check before building work?
Whether the property or its boundary wall is itself listed, which of the three conservation areas applies, and what the relevant council appraisal says about the street. Work affecting the setting of a nearby listed building can weigh in a planning decision even when the house itself is unlisted.
How we work on an instruction
Hampstead Chartered Surveyors is a RICS-regulated firm (RICS Regulated Firm No. 923064) working from its registered Hampstead NW3 office. The firm does not claim premises, staff or completed instructions in an individual locality, and it does not treat a neighbourhood name as evidence about a particular building.
An instruction starts with the full address, the decision the client faces and the documents already available, such as leases, drawings, notices or earlier reports. The scope, fee and inspection date are confirmed in writing only after that review, and access to roofs, lofts, basements or common parts is agreed before the visit.
Reports include RICS Level 2 and Level 3 home surveys, building and defect investigations, party wall appointments, reinstatement cost assessments, contract administration and schedules of condition. Each report records what was inspected, what could not be seen and what further investigation the evidence supports.
Public datasets such as the conservation-area register, the National Heritage List for England, British Geological Survey mapping, the Environment Agency flood map and Valuation Office Agency housing statistics describe areas rather than individual properties. They frame questions before an inspection; they never replace it.
Reviewed by Savas Bulduk BSc (Hons) MRICS, Director & Chartered Building Surveyor at Hampstead Chartered Surveyors & Building Consultancy. Last reviewed: . Our people · RICS firm record