Preheat oven to 140C/285F/Gas 1.
Place the flour and meat in a polythene bag and shake to coat the meat.
Heat half the butter in a deep casserole and fry the meat until golden and crusty all over. Remove the meat and set aside.
Add the remaining butter to the same pan and fry the bacon until crispy. Add the onions, thyme and bay leaves and cook until the onion has softened. Add any remaining flour and stir to combine.
Pour in the Guinness and stir vigorously.
Return the beef to the pan; stir to combine, add remaining ingredients and bring to the boil.
Cover the casserole with a lid and place in the oven.
Cook for at least four hours (or preferably overnight) until the meat is very tender.
For the suet dumplings, combine the first five ingredients, mixing well. Work to a paste with cold beef stock, adding just enough to bind all the ingredients. Season to taste.
Heat the remaining beef stock in a saucepan and bring to the boil. Shape the paste into 2cm/¾in dumplings and drop them into boiling beef stock. Cook until light and puffed up. This should take about 30 minutes.
Remove from the stock and add to your beef casserole.
For the mashed potato, simmer the potatoes in salted water for 12-15 minutes. Drain, then put the colander over the pan on a low heat for two minutes to dry the potatoes.
Return the potatoes to the saucepan with a pinch of salt and ground white pepper and mash until smooth.
Fold in the butter and warm milk and beat until combined. Check seasoning.
Serve the beef and dumplings with a dollop of mashed potato.