The two inboard shafts were driven by the high pressure ahead and astern turbines with the ahead turbines having an extra stage for cruising, this was separated from the main turbine by a bypass valve.
The two inboard shafts were driven by the high pressure ahead. Astern turbines with the ahead turbines was separated from the main turbine by a bypass valve. The ahead turbines were this. These ahead turbines were having an extra stage for cruising.