Even if you haven't the other 3 this would make a good decoration.   Much of the apparent corrosion is only transferred from the steel outer and will clean up.   Not sure which Bentley it fits but I guess from the 50's ?   If you can help please do .   Outer disc is   45 cm in diameter . The flat inner disc is 24 cm in diameter and the octagonal "nut" is 10.5 cms across flats.