What Donald Insall Associates does

Donald Insall Associates (DIA) is a London-headquartered architectural practice and heritage consultancy founded in 1958, specializing in the conservation and adaptive reuse of historically significant buildings. The firm offers four integrated core service lines — conservation architecture, heritage consultancy, new design in heritage settings, and townscape advice — delivered across eight sector specializations including historic estates, commercial, culture, education, faith, infrastructure and industrial, public, and residential. DIA's methodology is research-driven, grounded in detailed analysis of materials, construction history, and prior use to inform interventions that allow historic structures to evolve rather than simply be preserved.

DIA generates revenue through bespoke professional services engagements on a project basis, with bespoke pricing terms that are not publicly disclosed. Its go-to-market is direct enterprise and government field sales, targeting custodians of the UK's most significant historic buildings, commercial developers pursuing heritage-led schemes, preservation trusts applying for National Lottery Heritage Fund support, country estate owners, and local authorities. Notable flagship projects include the decade-long conservation of Westminster Hall, the Old War Office hospitality conversion, Chester Cathedral's West End Reordering, the John Rylands Library 'Next Chapter' transformation, the Camellia House at Wentworth Woodhouse, and Rochdale Town Hall.

In September 2024, DIA merged with Ferrey & Mennim — a historic conservation practice — to expand capacity for larger and more complex commissions. The same month, the firm achieved Certified B Corporation status and launched a refreshed brand identity positioning the firm around 'what heritage can be.' The firm operates as a private company, has no disclosed parent, and has not raised institutional funding; its customer base is UK-only and dispersed across multiple enterprise and government segments.

Name

Donald Insall Associates

Legal name

Donald Insall Associates

Website

https://donaldinsallassociates.co.uk

Company type

Private

Founded year

1958

Operating status

Operating

Headcount range

101–250 employees

Short description

Donald Insall Associates is a UK-based conservation architecture and heritage consultancy, founded in 1958, serving custodians of historic buildings, commercial developers, preservation trusts, country estates, and local authorities with research-driven conservation, heritage advisory, and new-design-in-heritage services.

Ownership category

akta.pro rank

Product category

Architectural Conservation Services

NAICS

Architectural Services (54131)

SIC

Services-Engineering, Accounting, Research, Management (8700)

akta.pro primary industry

Historic Preservation & Conservation Planning (BPAHAKAH)

Keywords

• Conservation architecture services
• Heritage building consultancy
• Historic building restoration
• Townscape advisory services
• Adaptive reuse architecture

Headquarters

HQ city

London

HQ country

United Kingdom

HQ region

Europe

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Marketing or Sales, Technology or R&D, Infrastructure, Others

Revenue model

1. Professional Architectural Services: Donald Insall Associates generates revenue through providing professional architectural and heritage consultancy services for conservation projects, new design in heritage settings, and townscape advice.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels3 records

Core offering

Donald Insall Associates is a UK conservation architecture and heritage consultancy firm that delivers professional services for the careful management of change to historic buildings. The firm provides four core service lines — Conservation Architecture, Heritage Consultancy, New Design in Heritage Settings, and Townscape Advice — serving custodians of significant historic buildings, commercial developers, preservation trusts, country estate owners, and local authorities across eight sector specializations.

Product overview

Donald Insall Associates is a unified service offering centered on conservation architecture and heritage consultancy, providing four interconnected core service lines: Conservation Architecture, Heritage Consultancy, New Design in Heritage Settings, and Townscape Advice. The firm specializes across multiple sectors including Historic Estates & Country Houses, Commercial, Culture, Education, Faith, Infrastructure & Industrial, Public, and Residential. The services are delivered as an integrated consultancy offering, where each service complements the others to provide comprehensive heritage solutions—from initial significance assessment through conservation planning to new design interventions. The merger with Ferrey & Mennim and B Corp certification reinforce the firm's commitment to responsible heritage practice.

Differentiator

Problem solved

Functional benefit

Products and services

• Conservation Architecture Expert architectural services focused on the careful management of change to historic buildings, grounded in deep research of materials, construction, history, and use to help structures evolve while maintaining their cultural significance and material authenticity.
• Heritage Consultancy Strategic advisory services that investigate what makes a place matter — origins, evolution, and architectural value — providing clear, robust guidance on how historic structures might adapt while preserving their significance.
• New Design in Heritage Settings Architectural design services for new construction or interventions within historic contexts, responding appropriately to heritage, materials, character, and use of the building or site after thorough investigation.
• Townscape Advice Strategic advisory services offering heritage-led input into the evolving shape of cities, towns, and landscapes, helping clients understand the broader urban and rural context of their projects.
• Historic Estates & Country Houses Services Specialized architectural and consultancy services for private country estates and historic residential properties, including conservation, restoration, and adaptive reuse projects.
• Commercial Sector Services Heritage-focused architectural services for commercial property developers and businesses, balancing contemporary commercial needs with historic building preservation.
• Culture Sector Services Specialized conservation architecture for cultural institutions including museums, libraries, cathedrals, and other public cultural buildings.
• Education Sector Services Heritage architectural services for educational buildings and institutions, including historic school buildings, university estates, and academic facilities.
• Faith Sector Services Specialized conservation and restoration services for religious buildings including cathedrals, churches, chapels, and other places of worship.
• Infrastructure & Industrial Services Heritage consultancy and architectural services for industrial heritage sites, infrastructure projects, and historic engineering structures.
• Public Sector Services Architectural and consultancy services for local authorities and public sector organizations managing historic buildings and public heritage assets.
• Residential Sector Services Heritage-focused architectural services for residential property owners, including conservation, renovation, and new build in heritage settings.

Quantifiable outcome

• Decade-long conservation of Westminster Hall completed

Named customers6 records

Segments5 records

Ideal customer profiles5 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Partnerships

One partnership is on record.

• Ferrey & MennimcoreStrategic or Co-development Partner · 18 September 2024Donald Insall Associates merged with Ferrey & Mennim, a historic architectural practice specializing in conservation and heritage architecture. The merger aims to enable larger and more complex projects by combining resources and expertise, reinforcing the company's commitment to conservation and B Corporation standards.

Scale indicators2 records

Recent moves4 records

Expansion highlights4 records

Broad incumbents

• Allies and Morrison: Allies and Morrison is a large, established London practice with a heritage and conservation team that, while broader in portfolio, competes for some of the same high-prestige heritage, civic and residential commissions as DIA.
• BDP (Building Design Partnership): BDP is a major UK multidisciplinary design practice whose heritage, civic and education teams address some of the same conservation and adaptive-reuse briefs that DIA serves, but at greater scale and across many more non-heritage sectors.
• Foster + Partners: Foster + Partners is a global architecture incumbent occasionally engaged in heritage settings and high-profile cultural and public buildings, occasionally competing with DIA on the same flagship cultural commissions (though typically on much larger, mixed-use scope).

Direct peers

• Purcell: Purcell is a UK-based architectural practice with the deepest specialisation in heritage and conservation architecture, operating at the same scale and serving the same custodians of significant historic buildings, cathedrals, university estates and country houses as DIA. It is the closest direct competitor for conservation-led commissions.
• Wright & Wright: Wright & Wright is a UK architectural practice with significant heritage, ecclesiastical and institutional projects (e.g., Lambeth Palace Library, Magdalen College), making it a direct peer in the cultural/education/faith sectors DIA serves.
• Stanton Williams: Stanton Williams is a London practice with a strong portfolio of cultural and heritage projects (e.g., Tate Britain, Royal Academy), competing for the same kind of publicly funded, high-craft conservation and new-design commissions as DIA.
• Caruso St John: Caruso St John is a UK-based practice known for heritage-sensitive new design and adaptive reuse (e.g., the award-winning New Art Gallery Walsall), overlapping with DIA's "New Design in Heritage Settings" service line and shared high-end cultural and institutional client base.
• Buttress Architects: Buttress is a UK conservation-focused architectural practice delivering restoration and adaptive reuse work across religious, civic, commercial and heritage estates, directly comparable to DIA's Conservation Architecture service line and similar client base.
• Feilden+Mawson: Feilden+Mawson is a UK architectural practice with a dedicated heritage and conservation team working on listed buildings, ecclesiastical and civic projects, directly comparable to DIA's conservation and faith-sector offerings.

Emerging players

• JTP (John Thompson & Partners): JTP is a London-based practice with growing conservation and placemaking credentials, including historic estate regeneration. It competes for some of DIA's mid-sized country-estate and residential heritage briefs while competing more aggressively on townscape and masterplanning.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights7 records

Customer concentration

• Xx.com/InsallArch

Compliance1 record

Revenue estimate

Valuation estimate

Number of profiles

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A1 record

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Donald Insall Associates