First the ingredients (haggis) (No, I don’t know what the “lights” are) Link

1 sheep’s stomach bag plus the pluck (lights, liver and heart)
1 lb Lean Lamb
6 oz Oatmeal
8 oz Shredded Suet
2 large Onions, chopped
about 1/4 pint beef stock

Now to make it.

Soak the stomach bag in salted water overnight.

Place the pluck (lights, liver and heart) in a saucepan with the windpipe hanging over the edge. Cover with water and boil for up to 2 hours hours. Impurities will pass out through the windpipe and so you need to put a basin under it to catch any drips. Drain well and cool. Remove the windpipe and any gristle or skin..

Mince the liver and heart with the lamb. (Add some of the lights before mincing if you wish.)
Toast the oatmeal gently until crisp and pale golden brown.

Combine the suet and onion with minced mixture. Season well and add enough stock to moisten well. Pack it all into the stomach bag, filling it just over half-full as the stuffing will swell during cooking.

Tie the bag tightly with string. Prick the haggis all over with a needle to stop it bursting as it swells.
Put an upturned plate in the base of a saucepan of boiling water, stand the haggis on this and bring to the boil, and let it boil slowly for about 4 hours.

Makes enough for 6 to 8 helpings of delicious haggis.