Preheat oven to 350 degrees.
Season the flour with salt and freshly ground black pepper. Add the beef, toss to coat.
Heat the oil and butter in a large casserole on your stove and fry bacon until crisp. Remove bacon from pan and then fry beef in oil and butter mix until golden brown.
Add the bacon, vegetables, herbs, stock and stout to the beef and bring to a simmer on the stove. Cover and transfer to the oven for 1 hour and 15 minutes (alternatively, keep cooking on the hob for 1 hour and 30 minutes). Add the mushrooms. Continue cooking for a further 40 minutes.
Once cooked, adjust the seasoning to taste.
Serve Beef and Guinness topped with Colcannon mash.