I don't think it even went to Portsmouth at all. It started from Rotherhithe, went via Southampton, Dartmouth, and Plymouth. Can't find anything about it stopping off at Pompey.
Thanks for letting me know, this was something I didn't double check and just relied on something I've heard/read... clearly a mistake! Updated the quiz to reflect this :)
I was aware of Merseyrail, not sure why I counted it as a separate thing in my mind. As for Newcastle's underground railway, completely unaware of it despite having visited several times! I have updated the quiz to reflect this :)