I'll go for 10 leaving Calais - 9 returning.
I reckon the group stayed together thru France - then 1 of them - lets say Darkhorse left the group & made his own way thru Spain.
At Madrid things would have got a bit iffy with the group getting split up into a few groups
One of them - which is why I say 9 return - who hasnt got a GPS gets totally lost in Madrid for a great length of time.
When he finally gets out on the road to Granada he gets delayed in a massive thunderstorm.
After the thunderstorm he gets totally stopped in an horrific hailstorm which brings him to a complete standstill - putting 2" of hail on the road.
Anyway after all this - with about an hour before dusk - he sets off again only to find that his headlamp has blown.
After fixing the light this poor unfortunate wretch is now approx 3 hours behind and 200 miles behind the others.
Darkness is now almost upon him so with the greatest of regret he gives up the chase & goes to indulge in the luxury of the local Parador for the night
Anyway enough of this - I'm off to the shops to buy a GPS
