Very slow cooked lamb shoulder

I've had lamb shoulder on the mind ever since our last visit to Cumulus Inc. So...when I saw lamb shoulders at the local woolies yesterday, I grabbed one with the intention of slow cooking it for lunch today. The preparations began last night. I had no idea how many hours I had to cook it for (should really have checked the internet for such things BEFORE I start cooking). Anyhoo...a whole two hours into the cooking process, I decide to check the lamb. The thing was still stone cold. Bloody fan forced option on the oven is not working. Panic. Fortunately, I realise that the 'bake option is still working fine so problem solved. A few more hours later, I go off to bed and switch the oven off. It is back on again this morning. The lamb bloody better be 'melt in the mouth' by lunch.