Mansion House opened as a four-track terminus in 1871. I believe that in 1884 the eastward extension for the Circle line service was achieved by extending the middle roads. My question is when was the westbound line slewed to cut through the platform and connect to the southern bay road. This allowed the centre road to be used for conveniently reversing trains, rather than the outer bay, which obstructed the westbound line as terminating trains crossed to enter. The northern bay road was lifted after the current Tower Hill was built to provide a central reversing platform with similar advantage. Of course the Mansion House middle platform road was lifted after the introduction of the S7 fleet. Until construction of the current building over the station in 1989/91, it was possible to glimpse the end of the southern bay road with original protective fencing behind the cable runs and advertising billboards. I wonder how long this lay abandoned in the centre of the City.
Its still there in parts behind the eastbound platform, where the IMR currently is would of been the crossover
Behind the eastbound must be the northern bay road, which was abandoned when Tower Hill centre bay road came into use. I am talking about the southern bay road which was adapted as the current westbound road. The amputated end to the bay remained partially hidden in the south-east corner of the station site.
Maybe on the Harsig site? I certanily remember both bay roads at Mansion House. The inner rail bay was taken out of use by 1970 when I started on the DR, but the centre bay was certainly in use until I left the dR in 1973.