The HIghwaycode website (
http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_069860) lists the rules as follows:
Parking at night
248
You MUST NOT park on a road at night facing against the direction of the traffic flow unless in a recognised parking space.
[Laws CUR reg 101 & RVLR reg 24]
249
All vehicles MUST display parking lights when parked on a road or a lay-by on a road with a speed limit greater than 30 mph (48 km/h).
[Law RVLR reg 24]
250
Cars, goods vehicles not exceeding 1525 kg unladen weight, invalid carriages, motorcycles and pedal cycles may be parked without lights on a road (or lay-by) with a speed limit of 30 mph (48 km/h) or less if they are
* at least 10 metres (32 feet) away from any junction, close to the kerb and facing in the direction of the traffic flow
* in a recognised parking place or lay-by
Other vehicles and trailers, and all vehicles with projecting loads, MUST NOT be left on a road at night without lights.
----------------------------------------------------
My modest sized coachbuilt weighs 2600kg unladen so it cannot be parked on the road at night without lights. Hope that helps, Steve