Flat 3, 23 Onslow Square, London, SW7 3NJ
About Flat 3
Flat 3 is a mid-terrace house in London (SW7 3NJ). It has a recorded floor area of 64 m² (around 689 sq ft), construction records dating it to before 1900 and council tax band G. The latest certificate (September 2024) shows a C (score 75), near the top of the C band. The rating has held steady at C across 4 certificates since October 2008. Between certificates, wall efficiency went from Very Poor to Poor and lighting went from Very Poor to Very Good. The recommended improvements would push it to B (score 82).
Across 1997–2023, sale prices on this property compounded at 7.4% per year. Today's modelled estimate of £1,492,000 is 46.7% below the 2023 sale of £2,800,000, running counter to the wider postcode trend, which makes the EPC and condition history especially worth a look. On a £-per-square-foot basis, the last sale (£4,065/sq ft) was about 455.3% above the typical sold price in the postcode. 7 planning records sit against the property, 6 approved, 1 refused. The record references listed-building consent, which constrain future alterations. At 64 m² it sits well below the postcode median (110 m² across 35 EPCs), making it one of the more compact homes locally. Sold May 2023 for £2,800,000.
Know exactly what you're buying at Flat 3
Before you offer, see what the listing won't tell you, the true value, the red flags and the full history.
Already flagged here
Launch offer · save £5
Valuation
against the asking price
Risks
planning & flood
Sold prices
similar homes nearby
Trends
the local market
Energy performance
EPC Rating
Property Improvements
Changes detected from historical EPC data
Heating controls changed
Hot water efficiency decreased
More low energy lighting installed
Heating controls upgraded for better temperature management
Hot water efficiency improved
Wall insulation improved
Low energy lighting percentage decreased
Heating controls upgraded for better temperature management
More low energy lighting installed
Planning history
Flat 3 has multiple listed-building consents on file — alterations need formal heritage approval.
- Aug 2020ConditionsIn report
Details required by Condition 2 (submission of details - e) repair/works to windows) of Listed Building consent LB/19/06772 (Full refurbishment of dwelling with minor alterations to layout)
Listed- Documents
- 7 docs on file
- Reference
- CON/20/02889
- Feb 2020ConditionsIn report
Details required by Condition 2b (new electrical service), 2c (new cornices), 2d (new skirting), 2e (repairs/works to windows), 2f (new doors and architraves) of listed building consent 19/06772(Full refurbishment of dwelling with minor alterations to layout (Listed Building Consent only)
- Council
- Thurloe and Smith's Charity
Listed- Documents
- 8 docs on file
- Reference
- CON/19/08221
We flagged 2 things worth checking at Flat 3
Independent checks surfaced things a buyer would want to understand before offering. The report explains each one in full, with the underlying data and what to ask.
- Signs of HMO activity in the area
- Larger development activity nearby
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Sales history & valuation
Price for Flat 3 has grown more than fourfold since the 1997 starting point.
£1,492,000
Modelled from EPC, postcode comparables and a sale-price growth of 7.4% per year over 25 years.
£2,800,000
Growth on file: 7.4% per year over 25 years.
Sales timeline
18 May 2023Most recent
£2,800,000
+1.8%over 5 years3 August 2017
£2,750,000
-3.5%over 2 years31 October 2014
£2,850,000
+533.3%over 16 years4 December 1997
£450,000
Median price across the last 5 sales in SW7 3NJ: £2,300,000 (2024–2021).
Nearby sales in SW7 3NJ
Flat 2, 23 Onslow Square, London, SW7 3NJ
Sold Nov 2024
£2,825,000Flat 12, 25 Onslow Square, Kensington And Chelsea, London, SW7 3NJ
Sold Oct 2024
£560,000Flat 11, 25 Onslow Square, Kensington And Chelsea, London, SW7 3NJ
Sold Jul 2023
£1,600,000Flat 1, 17 Onslow Square, London, SW7 3NJ
Sold Aug 2022
£3,600,000Flat 1, 11 Onslow Square, London, SW7 3NJ
Sold Mar 2021
£2,300,000
Everything we know about Flat 3, in one report
What it's really worth, what could be wrong, and the planning, sales and area data in full.
What we flagged
- Signs of HMO activity in the area
- Larger development activity nearby
Versus other Onslow Square homes
Flat 3 outperforms the street on price per m² by a wide margin.
Price per m²
£43,750
Street avg £15,824
Floor Area
64 m²
Street avg 106 m²
Habitable Rooms
4 rooms
Street avg 4 rooms
CO₂ Emissions
1.7 t/year
Street avg 4.2 t/year
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The neighbourhood at a glance
Rail-style transport is unusually close for this postcode.
Crime
10/mo
Rising year-on-year across the wider district.
Nearest stop
0.1 km
Onslow Square — bus stop.
Closest school
0.3 km
Oratory Roman Catholic Primary School. 58 schools nearby.
Go deeper on the local area
The full report breaks down crime, transport links, schools and air quality in depth.
Road noise across the postcode
Daytime· 07:00 – 23:00
58.4dB
Night-time· 23:00 – 07:00
48.1dB