Gauge of railways and motive power
7. The railways shall be operated on a nominal gauge of 1.435 metres (4 feet 8 1/2 inches) and the motive power shall be steam, diesel, diesel-electric, internal combustion, electric battery, or such other motive power as the Secretary of State may approve:
Provided that nothing in this Order shall authorise the Museum to use electrical power as motive power on the railways unless such power is obtained from storage batteries or from a source of generation entirely contained in and carried along with the engines and carriages: Provided also that, if electrical power is used as motive power on the railways, such electrical power shall not be used in such a manner as to cause or be likely to cause any interference with any telecommunications apparatus (as defined in Schedule 2 to the Telecommunications Act 1984(1)) or with telecommunication by means of any such apparatus.