Ok guys, some exciting new game stats:
Music: 100%
Dialogue & voices: 99.9% (still need to tweak volume here and there)
Graphics: 99.9% (touch-ups here and there)
Scripting: 99%
Thanks to all those who have got in touch recently re credits.
I'm really just at the 'bells & whistles' stage. I actually revisited the source material (the original 1983 Sleuth via a Let's Play vid) for inspiration and recalled you got a 'Sleuth ranking' once you'd successfully completed a game. Here's my proposed rankings in order of competency:

Can anyone suggest a category between 'incompetent' and 'rookie' ?