My T350c is cosmos blue and did cause a few issues when I wanted the front end Redoing as the paint codes didn't match. Got it sorted in the end and found out it was apparently a rare colour on T350's but don't remember the code!
I had a Cosmos Blue Chimaera. It was subtly different from a Cosmos Blue Griffith I parked next to once at a meet. I suggest you contact the paint supplier in Blackpool which employs an ex-TVR paint guy. They will be able to supply the correct match.
I've been trying to find out the same thing. Mine is stated in the handbook as being Starmist Cosmos Blue yet it look pretty much the same as yours does Barry. I've looked through all the info on paint codes on here and TVRCC but as you say, none of it seems to make any sense!