Thanks for all your replies gents. The final a/c C of G position only varies by 3/4inch, depending on which figure I use which, as stated by someone, is not a great deal. However with 4 heavy crew on board, the company figure puts the a/c just in limits, whereas my figure puts it just outside.
Nick says that the limits are an approximation, but what do you say to the nice AAIB/NTSB man when he asks why you took off out of C of G limits.
Apologies if I'm making a mountain out of a molehill, but it's more the fact that there appears to be a large discrepancy in the seat position rather than the final C of G. If the engineers have got that wrong, are there any more errors. And yes, I am trying to get an answer from them.
Finally, TC, there's a similar thread on the Air Support Forum.