Close collaboration between WHS Halo designers and the London borough of Islington has resulted in a bespoke System 10 vertical sliding window in pvc-u being approved for conservation sensitive areas. The strict requirements of the council?s planning department posed a number of design and technical challenges. The new vertical sliding window is said to not only emulate the visual characteristics of a traditional window, but has many benefits derived from the technology used. Key features of the new windows include Georgian bars, travel stops and decorative horns designed to replicate exactly the original products. The window also features the option of either releasable or permanent restrictors; a tilt facility to allow easy cleaning from the inside, improved security locking, a night vent position, and good thermal capabilities. So far, the authority has commissioned over 240 of the new, bespoke windows, which are used as part of the area?s housing improvement programme.