So you thought that the Rule Book was, er, a book of rules that you have to follow? We thought so too, but it seems that we might have been wrong.
Apparently, a Rostered Duty Officer (a what?) can bend the rules if s/he carries out a "dynamic risk assessment" in "real time". At least, that's the explanation that management finally came up with to justify an incident ealier this year when a faulty Picc line train was propelled from the rear with no direct communication between the people at the rear and at the front.
If any manager tells you to do something unsafe and quotes "dynamic risk assessment", then remember your right to refuse on safety grounds. And while Tubeworker would obviously never condone breaking safety rules, we'd suggest that if a member of staff does do something wrong, management will only have themselves to blame if that staff member claims in their defence to have made a "dynamic risk assessment".