There are general exemptions which allow a vehicle to park in contravention of the restrictions for as long as is reasonably necessary.
This could be to allow:
the vehicle to be used for the collection or delivery or the loading or unloading of goods from the vehicle. Loading or unloading must be a continuous process that takes no longer than necessary, or the vehicle may receive a Penalty Charge Notice (PCN).
'statutory undertaker' (utilities) vehicles if they cannot be parked in any other road to carrying out essential works. The vehicle is only exempt when it is considered necessary for the type of work that is being done. The civil enforcement officer will assess the situation to make sure the vehicle really needs to be parked at the location.
We do not give permission to park on the highway. You will need to satisfy the civil enforcement officer in the area that you are parked that you:
are making a delivery, loading or unloading, or
require your vehicle as an essential part of your work, which means it is being used as a workstation
The civil enforcement officer will observe your vehicle for a period of time and, if they observe no activity, may issue a PCN.
Important: Where loading restrictions are in place, no exemptions apply.