[E,. Anglia and sout-east being Belgic, i.e. inhabited by Belgic tribes from the continent]
I have definitely read it. I think some evidence comes from Caesar's Gallic War's, but from what I've read, he only really gives hints & perceptions, and I don't think we can make too many certain judgements about this.
I just wanted to say there have been some fascinating posts above. I'm not an expert, so I won't make any too specific comments about them; some tie in with what I've read in the past; others less so, but that doesn't mean they are wrong. A fascinating topic about which we will never have complete knowledge.