We bought a grade 2 listed house four years ago complete with revolting diamond glazed upvc windows. From what I can gather, the windows were installed before the house was listed. We now want to extend the house and intend to replace all the windows. However, we have grown quite used to having double glazing and would ideally like to replace the existing windows with double glazed wooden windows. The diamond glazing are completely out of keeping as we found the remains of the original windows in the garden. They only had one glazing bar (Sussex windows?). I haven't had the conservation officer in yet but would be interested if anyone has any thoughts.