He says: "Not sure it's worth the fiver they're charging as you could just get on the train and look out of the window. I suppose it does include admission to the museum and a mini-guided tour of the stations."
The tours run every hour from 1pm up to 4pm from Rotherhithe tube. Great for all history buffs and you'll be able to descend into "the beautiful road to Hades" as a Victorian actress said. Full details on the tour here.