I tend to do my roasties a slightly different way. I don't toss them in fat. That gives it too much chance to soak in. What I do is... once the potatoes are par-boiled, drain them, put them back in the pan, add some salt and pepper, put the lid on the pan, and shake it vigorously for a good 20-30 seconds. That will fluff up the edges. Then, instead of tossing them in fat, put a moderately thin layer of fat into the roasting tray and pre-heat it until it's smoking hot. Kind of like you're making Yorkshire puddings.
Then put in the fluffed up potatoes and cook as stated. Turning a few times. That makes them even crispier and yummy.
Lamb is my second favourite meat, behind beef. A couple of years ago, a supermarket chain here called Aldi were doing whole legs of lamb for like £3 post-Easter (they're normally 5-10x that much each) so I filled half my freezer with them, lol.
