I think you are confusing two different issues. Grades1, 2 and 3a land might be considered green belt but they are not officially classed green belt. Land that isnt high quality farm land can also be green belt.
As I mentioned in my previous post if its not green belt/barrier in the Council’s local plan it isn’t green belt or barrier. Grades 1, 2 and 3a land are given some, but separate protection, but it isn’t as strong as green belt status. They are only protected unless there is a clear need for a development. Despite what people think there is actually a huge shortage of housing in Wrexham according to Welsh government figures.