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<\/p>\n\u2018They convincingly demonstrate that heritage-led architecture is not a niche discipline; it\u2019s an essential part of how the profession has to respond to the climate emergency,\u2019 said the judges, who described the practice as leading the profession in this kind of work as it becomes more mainstream.<\/p>\n
\u2018You can see their impact. They are clear on their identity and it feels tangible and of the time,\u2019 the judges said. \u2018They are not paralysed by the heritage piece. They are really good architects. They do it all very\u00a0well.\u2019<\/p>\n
Visiting the practice\u2019s classy offices in the former Chilean Embassy in Devonshire Street, central London, any initial impressions of a traditional conservation practice are soon upended by 39-year-old chief executive Dorian Proudfoot and his passionate and thorough approach to reinvigorating the practice. The results \u2013 15 per cent growth in revenue and an extra 40 staff (taking it to a total of 150) over the last year \u2013 are tangible indicators of the changes afoot at the practice founded by Donald Insall in 1958.<\/p>\n
Proudfoot joined the firm\u2019s Chester office as an architectural assistant in 2011 and was made chief executive just over a year ago. \u2018We\u2019ve got quite a few lifers,\u2019 he tells me. \u2018I\u2019ve worked at every level in the practice, and I think that gives me some good empathy to my colleagues.\u2019\u00a0 That empathy comes across in his straightforward demeanour. His father was a stonemason, as is his brother. \u2018I\u00a0would love to reopen quarries,\u2019 he says. \u2018What\u2019s more sustainable than that?\u2019<\/p>\n
Keen to hone the practice\u2019s USP, Proudfoot\u2019s first move in his new role was to commission an external study to ascertain perceptions of the practice by current and prospective clients, staff, peers and the industry at large.\u00a0<\/p>\n
Dissatisfied with the answer that came back \u2013basically \u2018a safe pair of hands\u2019 \u2013 Proudfoot set about developing a rebrand with a new website and acronym (DIA) and a business plan. Since then, the practice has appointed a new head of communications\/marketing and a business development lead (a new position), upped its HR capability from one part-timer to three people, and hired a head of sustainability (not an architect). The practice aims to pay in the upper quarter of benchmarked salaries and\u00a0benefits.<\/p>\n
<\/p>\n
Reordering of the West Entrance of the Grade I-listed Chester Cathedral<\/p>\n
Source: James Newton<\/p>\n
The change in leadership coincided with a new generation moving up within the practice. Studio leaders were formalised into a senior leadership team, creating a platform for better collaboration. Proudfoot consolidated the practice\u2019s seven UK offices, which had previously worked as independent cost centres, into three regions. Offices in Bath and Cambridge were closed as people retired or projects completed.<\/p>\n
\u2018Retrofit is in our DNA,\u2019 says Proudfoot, \u2018but we\u2019ve never called it that \u2013 and actually we\u2019re still not calling it that.\u2019 His vision is for DIA to be the most sought after practice for complex heritage projects, setting the gold\u00a0standard.<\/p>\n
\u00a0\u2018We are deep subject matter experts, not generalists,\u2019 Proudfoot explains. \u2018I want everyone to find their passion. We\u2019ve got really nerdy people who are the absolute guru on a particular thing. We embrace our staff\u2019s passion to solve clients\u2019 problems\u2013 and the business\u00a0benefits.\u2019\u00a0<\/p>\n
With an astonishing 500 live projects on the go, the practice categorises its workload by client or client type rather than by sector. The top 20 clients generate 46 per cent of revenue. Not surprisingly, these include the Royal Household, the Crown Estate, heritage bodies such as the National Trust and English Heritage, and private estates, such as Blenheim. Other sizable projects include public buildings for local authorities, such as the recently completed Rochdale Town Hall. A stream of very small clients, including churches, require intermittent intervention.<\/p>\n
In addition, a busy heritage consultancy staffed largely by ex-conservation officers represents 25 per cent of the practice\u2019s revenue. The London team recently secured a blanket listed building consent order for Eaton Square, Belgravia, which enables residents to implement certain energy upgrades without an individual\u00a0application.\u00a0<\/p>\n
DIA\u2019s main target growth area is \u2018prime residential\u2019, country houses in need of physical repair, often being taken on by the next generation. \u2018They want a cosy house that\u2019s not going to cost an arm and a leg, whereas their parents used to just put on another woolly jumper,\u2019 explains Proudfoot. \u2018We need to make that house warm and liveable and sustainable, but also make money for them.\u2019 These clients have an urgent need to grow and diversify their revenue. The challenge is how to sweat the asset in an appropriate way and invite the public in. DIA is positioning itself as a one-stop shop for this market, able to simultaneously tackle repairs, environmental upgrades, enhance a building\u2019s intangible significance and deliver social value.\u00a0<\/p>\n
Conservation architects must, first and foremost, have a deep understanding of building fabric. Currently 43 per cent of DIA architects are conservation-accredited\u2013 just short of Proudfoot\u2019s target of 50 per cent. He views leading-edge sustainability expertise as central to DIA\u2019s future, and it achieved SBTi (Science Based Targets Initiative) validation in 2025. Environmental upgrades of building fabric have become increasingly sophisticated, with new modelling tools and sensors enabling more precise evidence-based interventions. Continual upskilling of staff is crucial \u2013 a cohort of 10 architects are currently undertaking Passivhaus training, and DIA offers its own internal conservation course. The practice is also trialling a sustainability framework that will soon be applied to all\u00a0projects.<\/p>\n
When asked about the biggest challenge facing the practice, Proudfoot reiterates \u2018changing the way we are perceived\u2019. Traditionally heritage was a bolt-on, but now it\u2019s about \u2018unlocking potential\u2019 \u2013 considering a building in the round, not as heritage police but as enablers of change. He cites B Corp certification, achieved in 2024, as having the biggest impact in attracting talent to the practice as well as driving social value in projects.<\/p>\n
Proudfoot recounts February\u2019s 100th birthday party for Insall \u2013 one of the few living architects with a knighthood \u2013 where the practice founder stole his mic to give a toast. Yet client expectations have evolved since the days when Insall visited clients in a Rolls Royce. Today, clients expect quality climate-resilient interventions that are economically and socially robust and secure a building\u2019s future. If the revitalised DIA is able to marry its attitude of overarching integrity \u2013 doing what\u2019s right for a building \u2013 with the complexity of evolving client needs, its success seems assured.<\/p>\n
Shortlist: the 2026 AJ100 Champions<\/p>\n
Foster + Partners
\nOrms
\nPopulous
\nSheppard Robson<\/p>\n
Judges<\/p>\n
Practice of the Year is selected from the AJ100 Champions cohort by the AJ editorial team<\/p>\n
Sponsored by<\/p>\n
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