Permission Secured for a Flat Extension in a Westminster Conservation Area
Planning permission secured from Westminster City Council for an extension to a first-floor flat in Marylebone, demonstrating compliance with conservation area design requirements.
PLANNING APPROVALSWESTMINSTERLONDON
Andrew Ransome
6/9/20262 min read
In 2014, Westminster City Council granted planning permission for the extension of a first-floor flat in Crawdoes Street, Marylebone.
The key planning challenge was demonstrating that the proposal respected the character of the conservation area, which was resolved through design-led justification and negotiation with the Council's development control team.
The Design Challenge in Westminster
Westminster City Council applies one of the most demanding sets of design policies in the country, particularly in its many conservation areas.
When a planning application was submitted to extend an existing first-floor flat in Marylebone, the central task was to demonstrate that the proposed development would complement rather than detract from the established character of the area and the surrounding flatted development.
Conservation areas require a high standard of design justification.
The planning case assembled for this application set out clearly how the proposed extension was sympathetic in terms of scale, materials, and appearance. Particular care was taken to show how the scheme sat comfortably within its setting and would not cause harm to the integrity of the conservation area.
Westminster City Council's development control team was engaged throughout the process. Ongoing negotiation with the case officer ensured that any concerns were addressed proactively before a decision was reached.
Internal Floorspace
The existing studio flat has an internal floorspace of 25 sq m.
Within the London Plan evidence base (Housing Space Standards, 2006) the recommendation was for studio flats to have a floor space greater than 31 sq m.
Whilst the application site predates these requirements, the proposed scheme provides an opportunity to bring the internal space in line with these policy requirements. The proposed internal floorspace would 42 sq m.
Planning permission was granted, with the Council satisfied that the proposal was acceptable in design and conservation terms.
Planning Application Advice
If you have a development project in Westminster or London generally and require expert planning advice, contact me to discuss how I can help secure planning permission and unlock your site’s potential.
Andrew Ransome MRTPI - Email: andrew@andrewransome.co.uk
About me
Andrew Ransome is a Planning Director and a Chartered Member of the Royal Town Planning Institute (RTPI), with more than two decades of experience in town planning.
He specialises in delivering strategic planning solutions for complex developments across both rural and urban environments, helping clients navigate planning challenges and unlock development opportunities. Connect with Andrew on Linkedin.
Planning Successes in London
Planning Application Information
Get in touch for planning advice: Email: andrew@andrewransome.co.uk
© 2026. All rights reserved.