But puppy, why would/should I want that? What I meant was that speaking English to my child doesn't come naturally; I don't communicate to children in English and find it hard. Same with cats and dogs - always Welsh!
Speaking English is no problem whatsoever for me - that's bilingualism for you. I dream in English if I'm dreaming about English friends.
So, first, I'm not excluding him and I'm not trying to stop DS speaking English.
Secondly, he will learn English, probably quite soon (he already says 'bye bye' and 'no' sensibly, and 'all day long' (from Wheels on the bus) quite randomly), and it won't be 'learning', just absorption.
This is true of all children who only hear Welsh at home; they all become fully bilingual. This includes children with learning disabilities (with some exceptions, obviously), children with Down's (I know one bilingual boy who has Down's), and, er, children who just aren't very bright (probably un-pc there, sorry) and ones who don't have an 'ear for languages'.
Omni good point about political issues - I bet if I said I was an Italian living in Italy and only speaking Italian to my DS who will be going to an Italian school etc etc it wouldn't be as much of a problem.
Onto DH - well, his Welsh is good, very good, and it's improving very, very fast. (Thanks to DS.) He has got a high-profile job in Wales because he had started to learn Welsh, and needs to keep learning. DH is not denying his background - born a Sais, will die a Sais, and supports England in all sporting events; but wants to understand the culture and background his son will be growing up in; and DH is being extreme in taking more than a casual interest in it! He was worried at first, that DS wouldn't speak English as well as he does, but has been reassured that he will. And he said it felt odd to start with - the aim was that he would try to speak Welsh when possible with DS, but it's funny, speaking to babies is a different register somehow - DH now can't speak to babies in English... (he wasn't exposed to babies or children before).
I should also add: DH and I speak to each other in English unless it's a basic level conversation 'did you put the laundry on and has it finished' etc; switching the language between the two of us will be a big step. So DS hears that, although strangely seems to largely ignore it.
DH also works away during the week so introducing English only on weekends could have been more problematic than DH improving his second language.
Finally, I have the best child psychologist specializing in bilingualism and language acquisition living next door... She says DS is bang on average, nothing special, and there will be no way of telling, once he starts school, whether he was brought up Welsh only/half and half/English only in his early years.