We didn’t have them at my vying-for-worst-in-the-town comp in the 80s/90s; we only just had a pretence at a uniform.
My eldest is at the same school now and it’s all blazers and prefects and head boy/girl. It’s gets marginally less shit results now, being 4th best of 8*.
We (sixth form college) will mention whether a student was HB or HG of their secondary school on their UCAS reference. No idea if it genuinely helps, but it’s never hindered them, to the best of my knowledge.
*Pleasingly, it beats the free school which was, until recently, a private school (source).