Make a foil parcel with the chicken legs in the middle of the parcel. Sprinkle a little salt on the legs. Make sure the foil is well folded over (no gaps), stick in a dish and cook in an oven (gas mark 5) for about 40 minutes. Open the foil carefully, if they are not done enough then cook them for longer.
I agree that cooking in liquid will give tenderest results. I had great results cooking chicken on the bone in a paella and keep adding liquid during the cooking and keep the lid on the pan either tight on or tilted.
Or if you roast do in a baking tray (stonewear is best) with water in the base. can cover whole tray loosely with foil to keep the steam in with the chicken. To make it tastey add thyme, garlic and lemon wedges and lemon juice.
The way my gran did it... except for the adjustments for fan oven that is.
Put them in a self baster with a peeled onion and a mug to mug and a half or so of water (hard to say... depends on amount of chicken and size of pan really). Cook at 160 for about 1hr 40mins in my fan oven.
They will be fantastically falling apart tender and still moist. Keep the juice that's left in the fridge overnight and then lift off the solid fat that will form. You will be left with a wonderful intense simple jellied stock.
Mrs R tried tinkering with this by adding tarragon etc, but eventuallly came to her own conclusion and agreed that the sheer clean simplicity of the chicken taste won out with this method.