Sliding sash windows up to four metres in height have been either restored or replicated by Original Windows Ltd, a member of the British Woodworking Federation, during a contract concerning a Grade I listed residential property facing Regents Park in London.

The specialist firm of joiners and carpenters based in Enfield, Middlesex, carried out the work to more than 90 windows at numbers Two, Three and Four Cumberland Place on behalf of Octagon Developments. Credited to John Nash, the architect whose name in synonymous with the royal park and its approaches, the buildings listed status and distinctive fenestration patterns demanded the greatest possible sensitivity and attention to detail.

About 25 of the century old box frames were reproduced by the joinery specialists following exactly the glazing pattern and sections of those being replaced. Three of these windows had to be bowed to the curvature of the building.

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The Director of Original Windows, Simon Matthews, is an advocate of the SPAB (Society for the Protection of Ancient Buildings) approach to restoration that encourages the minimum of alteration to existing fabric.

Aware of their responsibility to the environment they made use of softwoods from sustainable sources as no acceptable hardwoods were available at the time.

All the sashes from the windows that could be saved were removed to their Enfield workshop for stripping and sanding while sections of new timber were spliced in wherever this was necessary. Similar treatment was carried out in-situ on the box frames and the timberwork primed ready for finishing by decorators.

Original Windows obtained large quantities of crown glass rather than modern float glass for glazing all of the windows, ensuring the essential irregularity of reflection and slight distortion of light that gives an authentic

appearance. In order to offer the benefits of modern energy performance to the building's new occupants the BWF Member installed draught reducing brush seals at discreet positions along new timber parting beads and across the sash rails.

The Project Manager for Octagon Developments, Mr Rob Stone, commented: "This was a very demanding project, addressing a Grade I listed property that comes under the full requirements of the Crown Estate Specifications. Although we had never worked with Original Windows before, the quality the firm offered was very good and we are pleased with the level of service provided."