Heathrow Harry, to be even fairer your picture emphasing your comment about mid ranging American officers is of a 4* General.
To be even fairer still, the photograph features the very notable General Curtis LeMay - and a British DFC in addition to his US one, and so many others. No surprise there.
As high as it goes here in the UK.
Although five star promotions "lapsed" in 1995, Royal Family promotions such as The Prince of Wales excepted, there have been a trio of such promotions to honorary five star rank for former CDSs since, namely Charles Guthrie in 2012 and Mike Boyce and Jock Stirrup in 2014.
Jack