I saw the conversations above, and thought I had better join in... Before I go too far, I should say I dont know as much about the whole thing as I ought to. Its one of those things you dont appreciate at the time. But having said that, you are correct about GMIV being designed by Illingworth and Primrose. I believe my father was responsible for most of the design, with John Illingworth being primarilly resoponsible for the rig design, as was the norm in the design office. And you are corect about Angus being lost at sea in 1980. And as far as I know there have only been a few articles in the yachting press about him (See Classic Boat magazine by Ian Dear, not sure about the date right now), and allmost certainly no biography written (that I now about anyway). The one thing I do know about the whole project is that Angus and Sir Francis did not exactly see eye to eye. I maybe seeing things from the Primrose side of the fence, but I think Angus was pretty happy when the whole thing was over. The biggest falling out was when GMIV reached Austrailia, and Angus got a telegram saying that he had "proper designers design an new keel profile". Angus's reply was simple: "Just get on with it. If you've only reached Austrailia, she's not even run in yet". I think the rest is history. Having said all that, the one thing that really did make Dads blood boil was seeing GMIV, or any boat for that matter, being put in concrete. He would have been really happy to see her in the condition she is now (apart from the addition to the keel and rudder...!)
I hope this all helps a bit.
Dan