In section 80 of the [1967 c. 76.] Road Traffic Regulation Act 1967 (enforcement of certain traffic laws) there shall be inserted after subsection (9) the following subsection—
“(9A)In any proceedings in Scotland for an offence to which this section applies committed in respect of a vehicle to which any of paragraphs (a) to (d) and (f) of subsection (1) above is applicable, it shall be lawful to convict the accused on the evidence of one witness.”.