CarReg UK's local office in Belfast. Open to facilitate clients in the area who wish to collect or deliver important vehicle documents personally. Local History: OI 1 was first issued by Belfast County in 1904. Other combinations issued a century ago to the area include XI, AZ and CZ. Many prestigious historic private number plates come from this region. CarReg UK have been supplying personalised & private number plates for over 30 years. We are a registered DVLA number plates provider.