5. The circumstances referred to in regulation 4(b) are that the invalid carriage is either—
(a)stationary on a road, at any time, other than at times of danger due to another moving vehicle on or near the road; or
(b)in motion on a road which is a restricted road for the purposes of section 81 of the Road Traffic Regulation Act 1984 between 23.30 hours and 07.00 hours in the following morning.