After extensive research, and recommendations from friends, we narrowed it down to Ayrton and Box Sash
Both local companies who manufacture their windows in the UK, and both have extensive libraries of designs to give an historically accurate design to fit the period of your house.
Both have very high standards of workmanship and use the latest glass etc
The Box Sash quote came back slightly lower but Ayrton had a special offer to ‘buy now, pay in 6 months’ so we went with Ayrton
However we have more windows to replace in the future and will probably use Box Sash for those ones
A friend of mine works for a company who make terrific wooden windows, several of our friends have used them before and all praise the work they did. They're called Woodland of Kingston and i belive they cover most of south and west London heres a link to their site https://woodland-of-kingston.co.uk/