“(2A) In a prosecution for an offence under this section for driving a mechanically propelled vehicle, at a speed exceeding the built-up area speed limit or a special speed limit applying in relation to the vehicle, on a road in respect of which the built-up area speed limit or a special speed limit is indicated by one or more than one traffic sign within the meaning of section 95 of this Act, it shall be presumed, until the contrary is shown by the defendant, that the limit so indicated applied in respect of that road at the time when the offence is alleged to have been committed.”, and

“(aa) a general speed limit,”.