I think TonyNannini is still trying to find the description of the travellers. This comes from the clues not the grid. You need the eight letters before the missing points read in sequence of clues and the eight letters after the missing points read backwards.
Thank you drxx. Sorted now. Not a subject that I knew anything about, but a really well constructed puzzle.
I was a bit obtuse to say the least about the endgame , considering the speed at which I completed the grid yesterday.