Basement, 109A, Onslow Square has an Energy Performance Rating (EPC) of D. This is based on the most recent assessment, dated 26 Oct 2023.

The property is connected to mains gas and has single glazed windows. It is heated using a boiler and radiators (mains gas).

The most recent sale of Basement, 109A, Onslow Square completed on 17th September 2024 at £1,275,000 and was recorded by HM Land Registry as a leasehold flat.

Since 1995 the property has sold twice.

Values of comparable properties have dropped by 24.6% over the period since September 2024.

• Sold Sep 2024£1,275,000
• Sold Sep 2001£111,250

Since 2007 29 properties similar to Basement, 109A, Onslow Square have sold within a radius of 250 metres, per the Land Registry and our network of Estate Agents.

The latest, on the 23rd December 2025, was Flat 8, 20, Onslow Square, London, SW7 3NP, a leasehold flat which sold for £2,280,000.

Read more about house prices in SW7.

• Sold Dec 2025£2,280,000 | 3 Bed FlatFlat 8, 20, Onslow Square, London, SW7 3NPFlat 8, 20, Onslow Square, London, SW7 3NP
• Sold Nov 2024£2,025,000 | 3 Bed FlatFlat 6, 42, Onslow Gardens, London, SW7 3PYFlat 6, 42, Onslow Gardens, London, SW7 3PY
• Sold Aug 2024£1,250,000 | 3 Bed Flat81A, Onslow Gardens, London, SW7 3BU81A, Onslow Gardens, London, SW7 3BU
• Sold Oct 2023£2,600,000 | 3 Bed FlatFlat 6, 89, Onslow Square, London, SW7 3LTFlat 6, 89, Onslow Square, London, SW7 3LT
• Sold Jul 2023£2,600,000 | 3 Bed FlatFlat 6, 30, Onslow Gardens, London, SW7 3AHFlat 6, 30, Onslow Gardens, London, SW7 3AH
• Sold Dec 2022£875,000 | 3 Bed FlatFlat 18, 9-11 , Manson Place, London, SW7 5LTFlat 18, 9-11 , Manson Place, London, SW7 5LT
• Sold Oct 2022£1,518,000 | 3 Bed FlatFlat 6, 34, Onslow Gardens, London, SW7 3AQFlat 6, 34, Onslow Gardens, London, SW7 3AQ
• Sold Sep 2017£632,000 | 3 Bed FlatFlat 1, 81, Onslow Square, London, SW7 3LTFlat 1, 81, Onslow Square, London, SW7 3LT
• Sold Jun 2017£2,315,000 | 3 Bed FlatFlat H, 70, Onslow Gardens, London, SW7 3QBFlat H, 70, Onslow Gardens, London, SW7 3QB
• Sold Mar 2017£2,500,000 | 3 Bed FlatFlat 2, 89, Onslow Square, London, SW7 3LTFlat 2, 89, Onslow Square, London, SW7 3LT
• Sold Jan 2017£3,000,000 | 3 Bed Flat63, Onslow Square, London, SW7 3LS63, Onslow Square, London, SW7 3LS
• Sold Nov 2013£2,850,000 | 3 Bed FlatFlat 2, 53, Onslow Gardens, London, SW7 3QFFlat 2, 53, Onslow Gardens, London, SW7 3QF
• Sold Jun 2013£2,850,000 | 3 Bed FlatFlat 7, 97, Onslow Square, London, SW7 3LUFlat 7, 97, Onslow Square, London, SW7 3LU
• Sold Mar 2013£1,850,000 | 3 Bed FlatFlat 7, 89, Onslow Square, London, SW7 3LTFlat 7, 89, Onslow Square, London, SW7 3LT
• Sold Mar 2011£1,700,000 | 3 Bed FlatFlat 3, 35, Onslow Gardens, London, SW7 3PYFlat 3, 35, Onslow Gardens, London, SW7 3PY
• Sold Jan 2011£2,250,000 | 3 Bed FlatFlat 3, 89, Onslow Square, London, SW7 3LTFlat 3, 89, Onslow Square, London, SW7 3LT
• Sold Jan 2010£1,700,000 | 3 Bed FlatFlat 8, 35, Onslow Gardens, London, SW7 3PYFlat 8, 35, Onslow Gardens, London, SW7 3PY
• Sold Nov 2008£2,400,000 | 3 Bed Flat50, Rose Square, London, SW3 6RS50, Rose Square, London, SW3 6RS
• Sold Jun 2008£2,200,000 | 3 Bed FlatFlat 2, 35, Onslow Gardens, London, SW7 3PYFlat 2, 35, Onslow Gardens, London, SW7 3PY
• Sold Mar 2007£1,685,000 | 3 Bed FlatFlat 5, 89, Onslow Square, London, SW7 3LTFlat 5, 89, Onslow Square, London, SW7 3LT

Of the 321 addresses on Onslow Square, London, SW7, Basement, 109A, Onslow Square comes out as the 128th largest and the 133rd most expensive in our analysis of the public data.

It is also £43k more expensive than the average property across the SW7 district.

• Our Lady of Victories RC Primary School

  300 m away
• Oratory Roman Catholic Primary School

  400 m away
• Marlborough Primary School

  700 m away

• St. Thomas More Language College

  1.0 km away
• Chelsea Academy

  1.6 km away
• The London Oratory School

  1.7 km away

• South Kensington

  |

  300 m away
• Gloucester Road

  |

  500 m away
• Earl's Court

  |

  1.2 km away

The flood risk here is rated Very Low, based on Environment Agency data.