Lamb for Easter

Happy Easter everyone!
At Easter it is tradition at least in my family to eat lamb. Having this year enough people around the table I bought a leg of lamb. I was very enthusiastic about serving it until I realized I also had to cook it. Now how do I do that?
Of course I called the emergency number when it comes to cooking: my mum! She briefly explained how to do it. Basic rule: 15min in the over per 500g. Easy. She also told me to check the instructions of the oven to see what they suggest. Hum, "for 4 servings, 190-210 min"... now how many grams is 4 servings? and gosh 190-210 min that seems very long compare to any other recipe.
So here we go, 1h before lunch time and I'm facing the beast, or at least its leg. I prepared like they said in the recipe with the butter, the garlic and the rosmary; I put it in the oven for 45 min and fingers crossed I waited.
Of course after 45 min it was not cooked, well 75% there but the core by the bone was clearly still raw. We put it back in the oven for another 15min and took a break in the lunch until the lamb would be ready. Luckily for us those extra 15 min were enough. I was already picturing us waiting for 1 hour... and I asked the man in the house to slice it.
My first leg of lamb! and I did not take a picture of it before cutting it :( What was I thinking? You can see the slices of it on the dish on Wolfram's blog.

PS: Learning of the day: the oven is not as strong as we thought it was and extra time is sometimes needed.