A prime Hampstead mansion earmarked for conversion into 35 private flats is due to go before Camden's planning committee.

Developer 39 Fitzjohns Avenue Limited plans to convert Southwell House, in Fitzjohn's Avenue, into two studio flats, nine one-bedroom flats, 20 two-beds and four three-bedroom apartments.

It previously obtained permission for 20 flats on the site, which is sitting derelict, but is looking to increase the number to 35.

The application is recommended by officers for approval when it goes to committee on April 7.

Ham & High: Southwell House in Fitzjohn's Avenue has been sitting empty since it was bought in 2018Southwell House in Fitzjohn's Avenue has been sitting empty since it was bought in 2018 (Image: Andre Langlois)

In August 2019, an application for 20 flats went before the planning committee, which granted permission subject to a Section 106 legal agreement – which was was only completed last week.

A planning statement accompanying the latest application said the increase in the number of homes, which will be smaller, "is the consequence of the requirement to provide residential units of a size and scale that more readily responds to the market".

Cllr Oliver Cooper, leader of the Camden's Conservative opposition, said: "This plan does not include any affordable housing at all, so for the applicant to now ask for permission to make it more profitable is galling for local residents.

"This application would provide no affordable housing, eat up half the garden, and provide just four family-sized homes out of 35.

"Belsize and Hampstead need family homes, not just one-beds as Camden is eager to stack up at the O2 Centre too.

"Providing more one-beds will just over-develop the site and make the area less family-friendly. Camden shouldn't let developers make our area hostile to families."

Jenny White, acting chair of Netherhall Neighbourhood Association, said: "The redevelopment of the site will potentially have a very significant impact on the immediate area.

"We're all concerned to see that it's sensitively and respectfully planned in keeping with the character of the conservation area, and the garden is not lost."

Camden Council confirmed the absence of affordable housing, saying: "It was subject to a viability assessment which was independently assessed and which concluded that it was not viable.

"The approved permission is subject to a S106 clause which includes an affordable housing review mechanism, so if the viability position does change a payment towards affordable housing would be required."

Agent David Whittington, director of planning at Savills, was contacted for comment.