Newest cities in the Uk

The 2022 Welsh City is in the county of Clwyd. The county borough of {2022 welsh city} was deliberately and explicitly set up to not be considered a county, and the legislation that created it, and the other principal areas, preserved the old counties created 20 years earlier to be the counties for ceremonial purposes (which is what you are going with based on, say the city in Bucks, which is in a county of the name of the city for administrative purposes)

Likewise the 2002 Welsh City is in Gwent. The 2012 and 1994 Welsh Cities are a bit more complicated as their principal areas chose to be styled as counties.