Conservation architects and heritage consultants

 

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Donald Insall Associates

Conservation Architecture & Heritage Consultancy Practice



Founded over 65 years ago, Donald Insall Associates is one of the UK's most respected conservation architecture and heritage consultancy practices. Employee-owned and B Corp certified, DIA helps developers, landowners and local authorities unlock the potential of complex historic sites — balancing tradition and transformation to secure planning consent and deliver meaningful change across the UK's most sensitive built environments.

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Historic medieval stone castle with manicured hedges, topiary trees, and lush green lawns under a clear blue sky.

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Blencowe Hall, Cumbria

Conservation architecture, listed building
Transformation of a Grade I listed ruin from 25% to 100% habitable use — cited as an exemplar in English Heritage's Constructive Conservation in Practice and now generating £223k annually in local economic activity.
Modern A-frame wooden extension beside historic stone church with illuminated interior at dusk under dramatic blue sky.

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Private House, Llandwrog, Wales

New design in heritage setting
Award of planning consent for a contemporary new dwelling adjacent to a Grade II listed church within a conservation area, delivered for £170,000 through sensitive design inspired by the local vernacular.
Grand train station interior with arched glass ceiling, ornate columns, escalators, and crowds of people walking through.

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London Liverpool Street Station, London

Heritage and townscape consultancy
Supporting Network Rail's major redevelopment of Britain's busiest station as heritage and townscape consultant, navigating the Grade II listed station's complex historic fabric alongside ACME architects.

What we look for

Specialism

 

 

· Conservation

· Heritage consultancy

· Listed buildings

· Townscape

· New design in historic settings

Typical project size

 

· Boutique to major-scale across all heritage asset classes

Stage of involvement

· Pre-application

· Planning

· Design

· Delivery

· Public inquiry

Project type

 

· Listed building consent

· Heritage impact

· Regeneration

· New build

· Retrofit

· Expert witness

Geographic comfort

 

· UK-wide

· Oxford specialism

 

 

 

 

Open to connecting with:

· Developers

· Landowners

· Architects

· Local authorities

· Charitable trusts

· Historic England

What we deliver

Conservation architecture and heritage consultancy grounded in 65 years of experience — from listed building consent to major regeneration in the UK's most sensitive historic settings.


Rigorous heritage impact assessments, Conservation Management Plans and townscape advice respected by Historic England and local planning authorities nationwide.


New design in heritage settings that contributes lasting architectural value — from sensitive extensions and creative reuse to landmark new buildings within protected environments.

Opulent royal palace room with crimson walls, gold ornate ceiling, crystal chandelier, and elegant red velvet furniture.
Stunning aerial view of an elegant spiral staircase with golden steps and ornate iron railings in a classic building.
Architectural rendering of a modern brick courtyard with dining area, glass extensions, and slate roof under a cloudy sky.

How we like to work

DIA operates as a collaborative, research-led practice — embedding deep historic understanding into every project before a single design decision is made. As an employee-owned, B Corp certified practice, they bring long-term commitment and commercial awareness to complex briefs, working alongside architects, developers and planning teams to find solutions that are both viable and meaningful. With former Conservation Officers, Historic England Inspectors and specialist researchers on the team, DIA provides authoritative advice that carries genuine weight with planning authorities.

KEY CONTACTS

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Dorian Proudfoot

 

Chief Executive


Leads the practice and brings hands-on expertise in guiding clients through complex conservation, procurement and delivery challenges on large-scale heritage projects.

Smiling blonde woman in black top poses outdoors near historic stone building with arched entrance.

Helen Ensor

 

Director


Responsible for heritage consultancy across Oxford and the South, with over 20 years of experience negotiating consent on sensitive and complex historic sites for developers and private clients.

Professional businessman in gray suit and blue tie smiling confidently outdoors.

Simon Malam

 

Director


Leads on conservation architecture and listed building projects, with particular expertise in bringing challenging historic sites back into viable, sustainable use.

Connect with DIA

 

 

Project introduction form with contact details, role checkboxes, project type, services required, planning stage, and budget fields.
SEND YOUR ENQUIRY

Visit DIA's website →

Phone: +44 (0)2072459888

info@dia.co.uk

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Our Partners
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