Re: And this ladies and gentlemen...
Letter O is common enough in UK vehicle registrations. One of my past cars' registration ended MRO.
UK number-plate format rules do allow a letter O to appear in specific sections of the registration. Permitted sections depend on the format rules for the registration year of the car. The format rules used to change roughly every 20 years to allow for more registrations.
The current format rules are good for 50 years, and, again, allow letter O in specifc sections of the registration.