Because class distinctions didn't exist in 15th century Britain?!

This is simply nonsense.

No, just the particular fads, e.g., the one that drove the change to the non-rhoticity of RP, didn't exist in 15th century Britain.

That the current accent is driven by a particular fad aimed at highlighting upper class status doesn't imply that class distinctions are novel, just the particular effort to demarcate them (which wasn't durable, obviously, as RP isn't exclusive to the upper classes.)

Sure, accents are partly markers of social status, but it's quite wrong to ascribe the diversity of accents in Britain to this. There was never a period where everyone in Britain spoke with the same accent.

> but it's quite wrong to ascribe the diversity of accents in Britain to this.

No one, AFAICT, did that. The reference to “modern British English” is not, as I read it, a reference to “the current diversity of British accents”, but rather “the current dominant British accent”.

The current dominant British accent, if there is such a thing, isn't a marker of social status. If you're referring to RP, then hardly anyone even speaks RP nowadays (even the Queen only makes a half-assed effort...)

I would say accents in the UK are a combination of social status and location.

They're a combination of that pretty much everywhere, but it's not clear to me what the "dominant" British accent is supposed to be. If there is such a thing, it's probably some kind of fairly unremarkable Estuary accent that doesn't have any strong connotations of a particular social status.

"They're a combination of that pretty much everywhere"

Fair point - I would also agree that the idea of a "dominant" British accent seems a bit odd - certainly not in terms of what people actually sound like (rather than the broadcast media).

In 15th century England, the class distinction would be between speaking French or speaking English, not between different dialects of English.

If you are talking about speaking French as a first language, this is false, except possibly in relation to the upper reaches of the aristocracy. If you are talking about speaking French as a second language, then this continued to be a marker of class for a long time afterwards.

In a highly class-conscious society where the vast majority of people spoke English as their first language, it seems fairly unlikely that accent would have had no connotation of social status.

It thus seems hard to believe that the development of the modern diversity of English dialects would have been spurred by some sudden need to mark class distinctions.