The "railway" can extend to rail replacement buses, trains, stations and even land in the middle of nowhere.
Any railway employee can use reasonable force to detain you there if s/he thinks the situation requires it. This is quite often used, for example, to grab hold of someone attempting to run away.
Legally, you're covered, however, your employer may or may not approve of it.
Railway Revenue Protection Officers have much greater powers than any other transport provider, mainly down to the Conditions of Carriage, Railway Byelaws, Regulation of Railways Act 1889, Transport Act 2000, elements of PACE (Police Act 2005) which allow the Inspector to interview under caution and the Fraud Act 2006.
There is so much legislation available to back the "railway" up.