Cut the beef and kidney into very small pieces. Slice the onions. Toss the meat in flour and season well. Fry the meat and onions in a meat tin with a little dripping until the meat has changed colour. Pour on the stock and leave to simmer while the potatoes are prepared. Peel the potatoes and cut them into pieces about the size of an egg. Put them all over the meat, half below and half above the gravy line like icebergs. Cook at 325°F, 170°C, gas mark 3 for two hours until the potato tops are brown and the bottoms soaked in gravy.