Flat B, 23, Belsize Avenue has an Energy Performance Rating (EPC) of C. This is based on the most recent assessment, dated 08 Jun 2020.

The property is connected to mains gas and has mostly secondary glazing. It is heated using a boiler and radiators (mains gas).

Flat B, 23, Belsize Avenue last changed hands on 25th March 2021, selling for £1,123,296. The transaction was logged as a leasehold flat by HM Land Registry.

In total it has sold 5 times since 1995.

The market for similar properties has dropped by 14.4% since March 2021.

• Sold Mar 2021£1,123,296
• Sold Jun 2011£1,030,000
• Sold Oct 2004£610,000

Land Registry records and our Estate Agent network show 64 sales of comparable properties within 270 metres of Flat B, 23, Belsize Avenue since 2015.

Most recently, Flat 4, Roscommon House 2, Lyndhurst Gardens, London, NW3 5NP, a leasehold flat, sold at £1,200,000 on the 18th December 2025.

Read more about house prices in NW3.

• Sold Dec 2025£1,200,000 | 3 Bed FlatFlat 4, Roscommon House 2, Lyndhurst Gardens, London, NW3 5NPFlat 4, Roscommon House 2, Lyndhurst Gardens, London, NW3 5NP
• Sold Aug 2025£1,050,000 | 3 Bed Flat76, Belsize Lane, London, NW3 5BJ76, Belsize Lane, London, NW3 5BJ
• Sold Jul 2025£810,000 | 3 Bed FlatFlat 34, Belsize Court, Wedderburn Road, London, NW3 5QJFlat 34, Belsize Court, Wedderburn Road, London, NW3 5QJ
• Sold Jun 2025£887,500 | 2 Bed Flat12B, Belsize Park Gardens, London, NW3 4LD12B, Belsize Park Gardens, London, NW3 4LD
• Sold Jun 2025£1,150,000 | 3 Bed FlatFlat 4, 28, Belsize Park Gardens, London, NW3 4LHFlat 4, 28, Belsize Park Gardens, London, NW3 4LH
• Sold Mar 2025£1,050,000 | 3 Bed FlatFlat 3, 20, Ornan Road, London, NW3 4PXFlat 3, 20, Ornan Road, London, NW3 4PX
• Sold Feb 2025£1,135,000 | 2 Bed FlatFlat 3, 5, Belsize Avenue, London, NW3 4BLFlat 3, 5, Belsize Avenue, London, NW3 4BL
• Sold Jun 2024£1,137,500 | 3 Bed FlatFlat 44, Belsize Court, Wedderburn Road, London, NW3 5QHFlat 44, Belsize Court, Wedderburn Road, London, NW3 5QH
• Sold May 2024£1,075,000 | 3 Bed FlatFlat 3, Belsize Court, Wedderburn Road, London, NW3 5QLFlat 3, Belsize Court, Wedderburn Road, London, NW3 5QL
• Sold Apr 2024£1,325,000 | 3 Bed FlatFlat 33, Belsize Court, Wedderburn Road, London, NW3 5QNFlat 33, Belsize Court, Wedderburn Road, London, NW3 5QN
• Sold Feb 2024£1,090,000 | 3 Bed FlatFlat 1B, Wedderburn House 1, Wedderburn Road, London, NW3 5QRFlat 1B, Wedderburn House 1, Wedderburn Road, London, NW3 5QR
• Sold Dec 2023£1,312,500 | 3 Bed FlatFlat 48, Belsize Court, Wedderburn Road, London, NW3 5QHFlat 48, Belsize Court, Wedderburn Road, London, NW3 5QH
• Sold Apr 2023£1,085,000 | 3 Bed FlatFlat 47, Belsize Court, Wedderburn Road, London, NW3 5QPFlat 47, Belsize Court, Wedderburn Road, London, NW3 5QP
• Sold Apr 2023£1,135,000 | 3 Bed FlatFlat 7, Roscommon House 2, Lyndhurst Gardens, London, NW3 5NPFlat 7, Roscommon House 2, Lyndhurst Gardens, London, NW3 5NP
• Sold Feb 2023£1,200,000 | 3 Bed FlatFlat 5, Belsize Court, Wedderburn Road, London, NW3 5QLFlat 5, Belsize Court, Wedderburn Road, London, NW3 5QL
• Sold Sep 2021£1,180,000 | 3 Bed FlatFlat 1, 23, Belsize Park, London, NW3 4DUFlat 1, 23, Belsize Park, London, NW3 4DU
• Sold Nov 2019£1,286,710 | 3 Bed Flat54C , Glenloch Road, London, NW3 4DL54C , Glenloch Road, London, NW3 4DL
• Sold May 2019£1,160,000 | 3 Bed FlatFlat 1, 47, Belsize Square, London, NW3 4HNFlat 1, 47, Belsize Square, London, NW3 4HN
• Sold Oct 2017£1,232,000 | 3 Bed FlatFlat 2, 25, Belsize Park, London, NW3 4DUFlat 2, 25, Belsize Park, London, NW3 4DU
• Sold Sep 2015£1,295,000 | 3 Bed FlatFlat 2, 28, Belsize Park Gardens, London, NW3 4LHFlat 2, 28, Belsize Park Gardens, London, NW3 4LH

Our analysis of the public data ranks Flat B, 23, Belsize Avenue as the 149th largest and the 76th most expensive of the 446 addresses on Belsize Avenue, London, NW3.

Against the NW3 postcode district average, it is £243k less expensive than the typical property.

• Rosary Catholic Primary School

  400 m away
• Fitzjohn's Primary School

  600 m away
• Holy Trinity CofE Primary School, NW3

  600 m away

• The UCL Academy

  900 m away
• Haverstock School

  1.3 km away
• Harris Academy St John's Wood

  1.4 km away

• Belsize Park

  |

  400 m away
• Finchley Road

  |

  700 m away
• Hampstead Heath

  |

  700 m away

Environment Agency data suggests this area has a Very Low risk of flooding.