The platforms of Bayswater station were constructed in the trench and provided with a glazed roof. A short section of the trench was left unroofed to the west of the station to allow smoke and steam from the trains to escape from the tunnels. Even before the completion in 1884 of the continuous circuit of tracks which are now the Circle line, the MR and DR operated services through Bayswater as the "Inner Circle". The MR originally provided all of the trains, but from 1871, each company operated half of the service.