In the 40's and 50's many club bikes had horizontal dropouts which allowed manufacturers the ability to fit them with a variety of drives so that set up is authentic while the derailer hangar is just practical.

My 1955 Lenton could have been ordered as a three speed or as a fixed gear model... it would be very nice if it was fitted with an S3X (an ASC would be better) but in wanting to keep the bike original I will build up an S3X wheel for another one of my fixed gear bikes.

Pashley makes a beautiful bicycle and they warrant a higher price tag.