VELUX now have 2 offerings when it comes to windows for period properties.
The Conservation model is essentially no different than a standard VELUX window in its function and available in both centre pivot or top hung models. The main difference is they are finished in black externally and can include a glazing bar. Although limitations in off the shelf options exist the conservation style can be custom ordered in any size VELUX currently offer.
The Heritage model is a new addition and is intended to provide the ultimate in period appearance inside and out. The window is hinged at the top and opened using a winder mechanism not dissimilar to those used on cast iron skylights for nearly 100 years.