1926 Standard 18-36HP Saloon by Pytchley. Sliding sunshine roof demonstrator, not a "real" sunroof.
Joao has given the full correct answer and wins the point.
Pytchley Autocar Co. Ltd. of Northampton developed their sliding roof in 1925 and it soon became popular in the the industry and with the car-buying public.
In order to give the visitors to the 1926 Olympia Motor Show a better view of their 'sunshine roof', Pytchley presented this Standard 18-36 hp Saloon with a modified roof to illustrate how it looked and operated.