Parking on a junction

Over the past few weeks, these 4 vehicles from the same household have been parking on this junction. They have made it difficult for vehicles, particularly refuse trucks and deliveries vehicles to access the close, as well as sometimes making it difficult for us to get on/ off our drive. Not sure if it would impede any emergency vehicles trying to access the close if required. From my understanding they should not be allowed to park on the Junction as per the highway code. Speaking with one of the vehicle owners (whose actual parking is elsewhere) they state there are no restrictions on that part of the road and they're allowed to park there.