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Repairs secure St Mary's Church, Aylesbury for the next century

ablettTwo contracts at St Mary’s, Aylesbury, were undertaken together as a single project. The works included stonework repairs, repointing, leadwork repairs, window restoration and introduction of isothermal glazing, furniture and flooring repairs as well as renewal of the boiler flue and various other sundry works. The architect for the project was Daniel Benson of Ablett Architects.

The works were coordinated with great care, using experienced craftsmen and specialist firms to undertake the technically challenging and highly artisan-based works. They demonstrate the care and commitment brought to this project which has secured the building into the next century.

The stonework before repairs were carried out

The Grade 1 listed church of St Mary’s, Aylesbury, is a nationally important church. The ancient edifice has Saxon origins and has undergone many visible periods of growth, alterations and restoration resulting in the characterful and imposing church we see today. This large church dominates the town centre of Aylesbury and is situated in a walled churchyard ringed by historic buildings which, in effect, creates a setting akin to a Cathedral close.

Unfortunately, in the recent past resourcing to undertake various much needed repairs has been difficult. The 2015 and 2020 Quinquennial Inspection reports by the Inspecting Architect, Daniel Benson, have highlighted several serious issues including, on a general level, unsafe stonework to the clerestory walls and aisle parapets, buckled glass to the Chancel windows and issues with the lead roofs. Other, more specific issues to the church fabric included a stone gable cross (taken down as unsafe a few years previously), an unsafe and unlined boiler flue and badly decayed chimney and, in the chancel area, damaged misericords and small areas of missing floor tiles.

A project was put together that would address urgent stonework repairs at specific, concentrated areas and which gathered together and incorporated other necessary works which could sensibly be undertaken using shared access scaffolding. Having scaffolding to specific areas would allow for works other than the primary need to repair stonework and which included rebuilding the decayed chimney and flue, restoring the chancel windows and introducing isothermal glazing, replacing the missing chancel gable stone cross, renewing lightning protection tapes, restoring and redecorating historic cast-iron rainwater goods, and so on. As such, the scope of works was able to be a practical exercise in grouping much needed works of different types but in concentrated areas.


Repaired stonework

The main focus of the works was the removal and replacement of much decayed stone surrounds to the clerestory windows to the nave and transepts. Historic render repairs had weathered badly and were failing, exacerbating the decay to the stone behind. Definition of architectural detail was becoming lost at many windows. Generally, much of the clerestory stonework was badly weathered and decayed with several areas missing and others cracking away from the walls. Some jamb and arch stones were clunch (chalk) which had decayed more by than half the stones’ depth while in other areas the stones were cracking and pulling away from the walls. All the window surrounds were carefully surveyed and detailed drawings were made of the different profiles. Similarly, decayed hood moulds, string courses and parapet copings were surveyed and repairs scheduled. For the other elements of works, specialist advice was sought. This included the restoration of stained glass windows in the Chancel and the introduction of isothermal glazing to enhance thermal performance and preserve the delicate painted decoration and the insertion of an inflatable flue lining with the ancient walls (and new chimney which was completely taken down and rebuilt).

The project had a long gestation period which allowed for thorough investigations and research by the architect which informed the detailing and specifications. This including analysis of the walling stone and identifying suitable replacements with the help of The Bucks Geology Group and the Bucks County Museum. A source of the correct walling stone was found at a disused quarry on a nearby farm.

For replacement ashlar stone, Hartham Park stone was chosen for durability; the existing being a combination of different stones, including, as mentioned, very soft clunch.

Funding for the works was made possible by the happy convergence of several events including: a) a successful fundraising drive by the parish, b) the obtaining of a substantial grant from the Covid Recovery Fund and c) the Church Commissioners’ commitment to their liability towards chancel repairs.

Windows restored and with introduction of isothermal glazing

Teamwork and Collaboration

The project drew together a team of specialists and experts with whom the Architect was familiar and had worked with previously on other, similar projects.

The structural engineer was Robert Wallbank who advised on existing structure which could, for the first time in decades, be examined up close. This included inspecting a very large oak column in the Chapter House area which had several shakes and previous patch repairs. More prosaically, he checked that the roofs were suitable to support scaffolding and working areas and advised on how best to distribute the temporary loadings.

The buckled and fading Chancel windows were fully surveyed and restored by Martin Johnson Stained Glass (York) Ltd. The opportunity was taken to have them survey also all the windows at the church and a detailed report was obtained which included a history and description of each window, its condition, recommendations for repairs and likely costs. This will be invaluable for planning a future project to restore other windows. The Chancel windows, which formed part of this repairs project, were carefully removed to their workshops and dissembled before being restored and reassembled and then reinstated in new frames behind clear glass. This introduction of isothermal glazing provides both thermal improvement and protection for the delicate painted decoration on the stained glass, thus arresting further decay due to exposure.


New stone cross to chancel gable to replace broken original

The heating and flue lining works were overseen by David Gadsdon of Environmental Engineering Partnership. The badly decayed chimney was taken down and rebuilt with new stone incorporating an inflated flue lining within the existing wall and new connections to the existing boiler beneath the church.

The main contractor was Universal Stone Ltd whose team of expert masons demonstrated the skills and craftsmanship for which the firm is known.

Within the Chancel area, existing misericords had some damage and The misericord repairs were undertaken by Gavin Dingle of D & F Polishing who even gave a tutorial to the parish volunteers on how to refresh and polish woodwork generally so that other items of tired furniture in the church could be, and subsequently were, successfully rejuvenated by volunteers.

Coordinating the various trades, skill sets and staggered attendances on site along with coordinating complicated overlapping programs was a joint effort by the architect and main contractor and was successfully achieved through maintaining regular and detailed meetings to discuss the various threads of activities.

Outcome and Achievement

The successful completion of the works on time and on budget was a testament to the fore-planning and subsequent attention to the process on site. The various teams were all ‘on-board’ from the beginning and performed well together and independently.

The whole project was completed in Spring 2021 and commemorated by the Bishop of Buckingham, the Rt Rev Dr Alan Wilson, who publicly rededicated the new stone cross to the chancel gable, which represented a visible testament to the success of the larger project, in a public ceremony.


Decayed chimney before and after reconstruction and lining of flue

Thought Innovation

The process of ascertaining the right materials, skills, and team for the project was a long and dedicated process. Much thought was given to how to improve on some of the previous poor repairs and existing detailing. This process brought to the fore the expertise of various specialists including heating engineers, window restorers, geologists, lime mortar specialists and furniture restorers. The depth of knowledge exhibited by the various contractors added positively to the pool of intelligence and contributed to lively and informative exchanges regarding repairs and methodologies.


The project as a whole is a lesson in sustainability. The historic church has been successfully repaired and made secure for successive generations to appreciate and enjoy, and it will be able to continue its mission as a focus for worship within the Aylesbury community. Fragile and disintegrating details and decoration were saved by being fully conserved or repaired, deterioration to windows was arrested and the fragile glass protected and restored, replacing of missing stonework decoration keeps alive skilled crafts and trades. The finished results of the combined works have been a recognised success.

Team contact details

Architect: Ablett Architects Ltd, Kingfisher House, 21-23 Emfield Road, Bromley, Kent, BR1 1LT
Project Architect: Daniel Benson T: 0208 315 6619, email: This email address is being protected from spambots. You need JavaScript enabled to view it. or visit www.ablettarchitects.co.uk

Lightning Protection: Rodells Steeplejacks, Cell Barnes House, Cell Barnes Lane, St Albans Herts, AL1 5AS
Contact: James Marsden T: 01727 841 855, email: This email address is being protected from spambots. You need JavaScript enabled to view it. or visit www.rodells.uk

For further information visit www.ablettarchitects.co.uk