Put kettle on.
Put oven on to preheat to Gas 6.
Put oil in ceramic baking dish and put in oven to heat up.
Wash and chop spuds. Leave skins on. Parboil for 5 mins and drain.
Return to pan and shake about to fluff up edges.
Spoon into dishes with hot oil being careful of splashes.
Grind sea salt over and stir round well with a spoon.
Roast for 1.5 hours, stirring every 20-30 mins.
Here's the final result. On the left are the veg oil, on the right the EVOO. Chap thought initially that the veg oil ones looked crispier but I don't see much in it myself. I know I definitely preferred the flavour of the EVOO potatoes. Chap said on initial tasting the veg oil ones then on second try couldn't discern a difference.
Verdict - doesn't make a lot of difference but I prefer the taste of the EVOO ones so will continue cooking them with it.
Conclusion - my friend's talking rot - or at least as far as roasties are concerned!! :-D