It depends in what context. Certainly in some cases good English does matter. Although in general I am dismayed when children are corrected by teachers for using their local dialect. This leads to dialects dying out which is a pity.

I'm from Lincolnshire and I can see this happening rapidly. For the sake of 'good' English we are destroying a precious way of speaking.

The country will be dull indeed if a majority of us speak the 'queens English'. There will be less to discuss and love about the English language if such interesting ways of speaking are lost in time.

I don't think teachers correct dialect speech as much these days as they used to when I was at school in the Dark Ages: there was great concern in the '50s about the loss of local words and speech patterns. More important to loss of dialect is the 'one-size-fits-all' kind of speech that's often used on TV. This also contributes to the grammatical howlers often heard in everyday speech, but that's another topic!

These days, I think most accents are generally accepted in most places (my own native Brummie excepted, of course), though it's essential that children should be aware that there are 'standardized' ways to speak, so that others aren't prejudiced against them as soon as they open their mouths. One of the primary functions of language is to confirm one's identity, but it's also about communication: we all have to learn that other people may not be as comfortable with our speech patterns as we are, so we need a point of convergence.

I don't think we should be too concerned about loss of dialect speech because language changes all the time, and there will always be new and interesting dialects - Asian and Black English varieties spring to mind - as well as the rentention of older ones.

My favourite example of the tensions between 'standard' and regional English relates to a road sign in Yorkshire. In some parts of Yorkshire, 'while' is used to mean 'until' , as in 'We'll be here while 6 o'clock' or 'We'll wait while we've finished tea'. Now picture the road sign next to a level crossing, 'Wait while lights flash'...

I have just noticed how bad the English is in the first sentence of my initial post on this subject! Thank goodness I wasn't pushing a point on how important the use of good English is!

'While' is used in similar fashion in Lincolnshire. In the early days of unmanned level crossings, I seem to recall that it was deemed prudent not to use that word so that confusion and accidents could be avoided.

My Personal view on the language vs dialect debate is somewhat mixed. I can see how prescriptivism is useful when trying to teach to a certain standard, but I feel this is often pushed too far - with people claiming that a certain dialect or accent is 'wrong'.

There are many linguists who also hold the view that language should be described and not prescribed. This to me seems somewhat contradictory. Looking over a linguist's research papers, or publications, it is (usually) evident that they are adhering to a strict academic standard of writing. I remember there was an experiment done recently at Lancaster University where the lecturers allowed students to hand in assignments written in their local dialects. They had to switch back after a few weeks - as it was too hard to understand a lot of what they were trying to express!

It seems to me that perhaps written language is best prescribed (since it is man-made and artificial), whereas spoken language is more suited to being described (since it is more spontaneous and natural).