I’m not disagreeing that it’s a working clas slur, I know that. But you asked what the well agreed upon name is for that subculture is… and sadly it’s a slur. I’ve seen people describe themselves or their style using that word, I’ve been people put in dating profiles (both as a self description, and as something they’re looking for).

This fashion article uses it repeatedly (and acknowledges it’s contraversial origins as a word), but also uses “casuals”, “English working class youth” and “football hooligan” as subculture groups that wear that style of urban street wear.

If you don’t like it, don’t use it. But it is the common agreed upon term that you wanted to know. British society doest have quite the same issue with race as the USA, but It has a huge problem with classisim, and it is made much worse because people don’t even see it as a problem. You said that people wouldn’t Just describe a guy in dredds using a racial slur, but they would have 80 years ago. Britain is still at that stage with its attitudes to working class culture. And appropriately, “Chavs” by Owen Jones is a good introduction to people interested in the issue.