Using REX here, I'm half way across the pond from JFK to EGLL at FL410 (way too much chop on Eastern seaboard today).  I just heard my stick shaker going nuts and found the trim all the way up.  I did enter a stall and went to down FL360.  Now I cannot seem to accelerate beyond 180 indicated.  Set altitude to FL350 in a slow descent now building speed back up.