So where did this line go or come from? its looks as if it came of the Relief lines then underneath somewhere was it a terminal station
I think this article explains the use of the tunnel:
http://homepage.ntlworld.com/ms.draper/Talks_Reports/mr1300.html
The following I found from another forum might be useful to note as well:
There is an old maps site which might help, the BTF Blue Pullman London - Birmigham in 5 minutes or whatever it's proper title is would definitely help ifyou can stopp the frames in the right place (not too difficult).
The station buildings were on the overbridge with steps down to the platforms - all separate from the next door LT station on the H&C. The station originally had 4 platforms but these were reduced to the island serving just the Relief Lines about the time of the 1967 resignalling when the Down Main line was realigned to increase speeds.
Google Maps is probably about as much use as a chocolate teapot for this area as it has changed out of all recognition since the period you have in mind, just about the only constant feature is the H&C line with the BR bit having changed radically in the 1967 and again in 1992 layout alterations and resignallings. Crimea mileage yard has gone, St Evans Road Goods has gone (although it was more or less just a small nest of sidings by 1967) the connection over the H&C to get to Crimea Yard went a few years before the 1967 resignalling, Paddington New Yard (goods) depot building is still there on the upside above what is now the 'bus depot but the yard associated with it has gone and the track at the Westbourne Park end of Mousehole Tunnel (opposite Westbourne Parks station) has also gone of course.
I would suggest you look for a copy of Middleton Press 'Paddington To Ealing' by Mitchell & Smith, ISBN 1 981706 370 which has some Map extracts and quite a few illustrations