Captain Big Iron:
Blaming icing by itself seems unlikely to me. The 747SP flew up to 45,000 feet for 26 hours routinely for thirty years and never had any problems (that I know of.) It even completed a 54 hour flight. KC-135's B-52's and airborne command posts have remained aloft for days without any problems.
Also Concorde comes to mind. I know that the Investigation team is of the very best and the report is extremely thorough. But still, after millions of flights by both 747 and 777 aircraft on these routes in similar conditions, it does seen strange. I suppose that on this particular flight the holes in the Swiss cheese slices just happened to align perfectly?
There have been several other reports of 777 aircraft having engines not respond to commands in situations where ice is not likely to have been an issue. To those familiar with the 777, did these incidents also involve RR Trents and have these incidents been adequately explained?