Had a good think before posting this and thought, there must be others out there that this has happened to!
Only shot to present itself was to the back of the neck before he disappeared into cover, sent the 180 grain SGK bullet downrange from a prone position and it connected directly to the back of his head! His head and body were facing directly away from me. On closer inspection, his right antler was blown completely off which I later found minus half the brow tine.
The head wasn't medal standard but I'm still gutted either way as I clean all my 6 pointers up for reference purposes.
Probably should of left him be or aimed slightly lower, either way the shot was very humane.