2012, Andrew Martin, Underground Overground: A passenger's history of the Tube, Profile Books, →ISBN, page 49:
Before we reach the Circle saga, two other extensions of the Met need to be mentioned. The first is the Hammersmith & City Railway - now the western part of the Hammersmith and CityLine. It was built and jointly funded by the Metropolitan and the Great Western, even as they were arguing over operation of the Metropolitan.
