Highway authorities have no powers to remove vehicles if they display a valid tax disc.
Waiting restrictions can be considered, if the conditions for implementing such restrictions are fully complied with.
If it can be shown that the vehicle is creating an obstruction or a hazard then the police can take action on that basis.
If the vehicle has no tax disc it should not be on the public highway and the police can take action against the owner. The problem in these situations is often that the vehicle has been purchased by a dealer, but its transfer of ownership has not been registered and the vehicle is still officially registered to its previous owner.