He hadn't ever flown the accident route before. The route he had flown early in the day was from Shobdon to Caernarfon.
No, his outward route had been Shobdon to Colwyn Bay, then direct to Caernarfon. In the AAIB report it says that he discussed the route home, and they decided if they couldn't fly the direct route they would fly the reverse of their outward route.
I'm wondering....
Did the pilot perhaps not even think of following the coast? When you do your PPL, many instructors emphasise lines on maps and headings; track crawls and following line features are somewhat frowned upon. I agree it sounds crazy, but is it possible that the idea of following an unfamiliar coastline didn't even occur to him, if he'd never done it before? After all, he only had 116 hours. And with 12 done in the last 90 days, this could well be someone who learned to fly less than two years ago - an average 60 hours to PPL at an airfield well inland, then a year flying alone. And summer 2006 was unusually good, so he might not have been used to nasty weather in the montains, if he'd ever flown in them at all.
It makes as much sense as anything else in this sad episode. I intend to learn from it, and emphasise to my students that they can take any sensible route and plan it any sensible way, especially in bad weather. Though to be honest, in helicopters we do tend to do that anyway.