Being a working class gal (or maybe "under- class"!)
my friends and new aquaintances are often from the same background.However the moment they find out what type of schools I send my children to their attitude changes and the friendship ends because they distance themselves from me. Even my father doesn't talk to me because we have decided to send DC privately. He comes from a generation where many (not all) working class men did not want their kids to move above their station.
It is clear to me that he is consumed with issues of jealousy and low self-esteem.
Suncrest, you may well find that your friend begins to boast about how well her little darlings are doing at the fabulous comps and you will feel that you cannot do the same. If you want to remain friends then just humour her. However things may get worse (if she doesn't get over it - friends aren't always as decent as solimum) when DS gets more GCSE's or gets into a better uni or goes on some exotic trip. She'll criticise you again. She'll tell you you and your son has changed (believe me it happens) and you may well just feel very unhappy everytime you see her.
I even found myself justifying my choices to a stranger the other day - more fool me!
I was in a shop in a very working class town and the assistant asked why I was visiting. I said I was off to see X school (top school in county) and when I saw her face I mumbled that I heard they offered large scholarships for parents who couldn't afford the fees. So she assumed I was talking about my circumstances and was happy to chat although she warned me that people weren't as friendly "over there"! I doubt very much she's ever had much interaction with any of them!
Give me a few years and my cantancarous side will be fully developed so I won't give a monkeys what anyone thinks!