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Recent Projects

The Guildhall, Derry/Londonderry

This project 2012/13 involved the full restoration of many of the beautiful, historic stained glass windows at The Guildhall and included the repainting, firing and re-fitting of stained glass to match original damaged pieces.

The repair and restoration of the heritage glass and the fitting of secondary glazing at the Guildhall was not only an intricate job, but a nostalgic one.  Stephen & Lewis's father Jack Calderwood had first restored the stained glass windows in the 1970's after damage caused by the 1972 bombings and Stephen had assisted his father with the task at that time.

This current project involved the full restoration of many of the beautiful, historic stained glass windows at The Guildhall and included the repainting, firing and re-fitting of stained glass to match original damaged pieces.

The architect's brief for the acoustic secondary glazing was to provide as few mullions and transoms as possible, so that the beauty of the stonework and leaded glass was not interrupted.  The lower section of the glass also needed to be easily cleaned.   The problem was that the openings were huge - 2400mm wide x 5400mm high (8ft x 18ft).  

We designed a system of horizontal sliding, powder coated, acoustic secondary glazing fitted below a single pane of laminated acoustic safety glass.  These panes were 2400mm x 3200mm and had to be safely manoeuvred up two flights of stairs and lifted into place using specialist lifting gear.  This was something our competitors had said could not be accomplished and therefore they could not price for.  

The result is stunning and was exactly what the architect wanted.  The Council Chamber is now warmer and quieter, without obstructing the beauty of the stone and glass.

See for the history and more info on The Guildhall.

Below is an article from Derry City Council News 07.02.2011 regarding the ongoing restoration that year and is followed by a selection of photos of recent work from 2012/13 -



Expertise passed down through generations is ensuring that the stained glass in Derry’s Guildhall will retain the shimmering beauty that has cast light on proceedings in the city’s civic heart for almost a century.

Nearly 40 years ago Stephen Calderwood worked alongside his father Jack to preserve and restore the beautiful windows in the Guildhall after they were devastated in a bomb attack. Now he’s returned to the city’s most iconic building to make sure that the glasswork comes through the present restoration process, not just maintained but in some cases enhanced.

As Stephen explained, the extensive stonework restoration being undertaken on the building has necessitated the removal of a number of the windows – a job which requires painstaking care and precision on behalf of Calderwood Studios.

“Selected stained glass windows have to be removed for the purposes of stone work restoration and while that’s being done any defects in the actual glass will be attended to. The bulk of the restoration work is in relation to the stone work and in order for that to be carried out we have to remove the windows and take them away.

Initially what you have to do is to cut into the stone and remove the glass very, very carefully to ensure that none of the pane or borders get damaged. That’s the hardest part,” he said.

If a replacement piece is required, you first cut yourself a piece of coloured glass, then you build up colour, shading and tracing work in different layers and by numerous firings of the glass. It’s like any art work, you start with your base and you build up your pictures,” noted Stephen.

Of course, like the city itself, the stained glass in the Guildhall has survived many traumas over the years.

“The stained glass in the Guildhall has suffered over the years because of bomb damage. We restored the stained glass from a really bad state in the 1970s and a lot of the original glass was lost. It depends where the stained glass windows were located on the building’s elevations but up to 30 or 40 per cent of the glass was lost on some while others survived intact. A trained eye can tell the difference between the old and the new glass.

The Guildhall is fairly typical of stained glass in buildings and churches all over Northern Ireland many of which suffered damage during the troubles. What it does mean is that studios here in Northern Ireland are experts in repainting glass to match the original. In places like England or the Republic they wouldn’t have anywhere near the amount of experience in restoring stained glass that we have here,” he said.

For Stephen, working on the Guildhall is something of a labour of love, allowing him as it does to preserve the legacy of work carried out by his father: “I worked in the Guildhall for my father in the 1970s and never really thought that I’d be back doing it again. But the good thing is we are back doing it for the best of reasons this time. The previous restoration works have left the stained glass in excellent condition. This work is very rewarding, there’s a sentimental aspect and a bit of extra pride involved in working on glass that my father worked on nearly 40 years ago. It also means I have good background knowledge of the windows and am maybe a wee step ahead when it comes to working on them,” he said.

A particularly interesting aspect of Stephen’s professional inheritance from his father is the fact that he actually possesses the original water colour designs by Campbell Brothers for the windows which remain in almost pristine condition almost 100 years after their creation.

“It would be very rare to have original designs available, generally designs were just filed away somewhere and possibly lost or thrown out, so to have these is extremely rare. The designs would have been retained by the original studio that produced them around 1910 or 1912 and they have been handed down through several generations and that’s how they would have made their way to my father. He worked in Campbell Brothers, as did I, and three or four generations of glass workers would have kept them. I think now is a perfect time to produce them,” he said.

When all the restoration work is complete the windows will look as good as they did in 1912, and Stephen says they won’t need further restoration for decades to come.

“In the life cycle of stained glass, in the space of 100 years you would expect it to have been restored once or twice. It tends to be a 50 year cycle so these windows weren’t far off needing restoration at this stage anyway. They are now in very good condition and won’t need any work done on them for quite some time,” he said.