(1) Notwithstanding anything, to the contrary contained in any Special Act or Order, it shall be lawful for the owners or lessees of any railway generating station, or of any generating station erected under statutory authority for the purpose of working tramways or light railways, to supply electricity therefrom upon such terms and conditions as may be agreed—

1. (a) to a joint electricity authority; or
2. (b) to an authorised undertaker; or
3. (c) to any consumer, subject, in the case of premises situate within the area of supply of an authorised undertaker, to the content of that undertaker: