The Concorde story...
Have a close look at the Concorde forward fuselage (under the cockpit side windows). Strakes, chines, vortex generators... the formal name has been disputed.
Small slabs, that don't look very impressive.
But they generate a vortex on each side, that "folds" over the fuselage well before the forward end of the leading edge (so they're not associated with the wing vortex)..
At higher angles of attack those vortices "glue" the airflow on top of the fuselage right until the back, so the entire vertical tail remains "blown" properly - which explains in part why the Concorde vertical tail is relatively small.
Apologies...the only picture I could get my hands on to illustrate the effect is not very good... there are better ones.
But it's another example of how small bits and pieces right up front can contribute significantly to directional stability.
Oh, and, John, in this case it definitely wasn't a "fix". Those vortex generators were already in place on the first flight of the first prototype (001).
And thanks for your detailed tale about the HP115, I always wondered a bit about the engine intake at high AoA, but just didn't think it through fully.
CJ