Thank you everone once again. You all confirm that prep school is needed, and despite this not originally being my choice of action, your consistency of views is actually very reassuring.
Civil, you understand me approach to Eton very well stating - " If you're going to go private, you might as well go to Eton - much more different than a bog standard private school".
My approach to primary school was very similar to this, hence I opted for state school and not a prep school. My child is very happy there too, and many children get to grammars and various public schools (though I do admit that this being a VE CoE school it is probably not that representative of a standard primary school discussed on the BBC this morning).
I should also clarify that I wanted my son to go to grammar school for years 7 and 8, also in order to somewhat protect him from the "Eton bashing" that I often see even on this website and to which my son could be exposed to later in life. The world can be a cruel place to Eton graduates who do not make it to be PMs and MPs, or have no "old money" to fall on, and I figured it would be good if one day my son is able to identify himself with both the fellow Etonians AND the state school graduates. I would like him to be flexible here and somewhat immune to "Eton bashing" he could later experience. Not every Etonian will become a PM.
Undeniably I am still bit unexperienced with these issues (hence my almost silly questions on CE), but having seen Eton, Harrow, Winchester, and many other schools, I do think that a place like Eton, 1st choice public school for so many, can be absolutely great to prepare for the 21st century. Utilisation of time, ethos, sports, even somewhat outdated dress code, almost total separation from parents (no weekend boarding) - this is what I think my child needs in the times when we, the parents, are afraid to even allow them to walk alone down the road to the supermarket.
Also, perhaps not too humbly, I think that the fact that my son, state school educated, of immigrant background, was accepted, is in itself the best sign to me that the place is clearly adapting and being open to boys of various backgrouds. You know, contrary to many stereotypes, nobody asked me for a parent interview, display my bank statement, etc. It was always about him, and frankly I have little doubt that he will succeed there. I am only somewhat worried about this potential later phenomenon of "Eton bashing" - which probably has an impact on kids confidence in itself (some probably retreat into bunkers of fellow Etonians, while others appear simply overconfident), and hence I feel that a state school background will protect him from that too.
Hope this makes sense, and once again thank you for all your views. I will definitely speak to Eton Admissions now, but at least I will know better now what I am talking about rather than looking like a totally unprepared parent that admitingly until your advice I somewhat was.