in experimental, the LBSCR 4 wheel carriage is introduced in 1868 with a top speed of 110km/h, while its brake carriage is introduced in 1870 with a top speed of 120km/h. The regular carriage is useless without the brake carriage, so the regular version sits around in the depot for 2 years before it can be used.
in the standard version the carriage and brake carriage are introduced in 1870 with a top speed of 120km/h.
I think they work with the LBSCR class B1 gladstone which has a top speed of 120km/h and is introduced in 1882.
Thank you for your report - that is most helpful. The 19th century railway carriage (and, indeed, locomotive) time-line is still somewhat incomplete, so more work is needed in this area. However, obviously, the introduction dates should be consistent: I have set them to April 1872 for the time being, with a speed of 120km/h.