Hmm.. I remember being taught that countries had accents, and regions were dialects.
For example, you can have a Welsh accent, but not a Cardiff accent.
There is definitely a Cardiff accent, Jon, just as there is a Bristol accent, a Glasgow accent, a Birmingham accent, etc. Indeed, there are probably variations in accent even within cities (east v west, north v south).
Accents are how speech sounds, but dialects have more to do with vocabulary and grammar. The accent sings the song, but the dialect can change the words.