People tend to forget he was an Ulsterman (of Anglo-Scots blood), not English.
Very true. Lewis was most emphatically not English, and I think many details of his life - right down to having many worries in living with his brother, who declined into alcoholism - were all too typical of his ethnic background.
There is a book published on the Ulster background to Narnia. It has not been picked up by the critics, but they only support the big publishers. I recommend it:
http://www.freerepublic.com/focus/f-chat/3040627/posts