Tip the flour and mustard powder, if using, into a bowl, and beat in the eggs until smooth. Whisk in the milk, a little at a time, until all of it has been incorporated and the batter is lump-free. Add a little water if it is very thick. Season and set aside. Wrap a bacon rasher around each sausage.
Heat the oven to 220C/200C fan/gas 7. Drizzle the oil into a medium roasting tin or enamel baking dish, and put in the oven for a few minutes to heat up. Carefully add the pigs in blankets and tip back and forth to coat in the hot oil. Roast for 15-20 mins, turning over halfway through, until sizzling and browned.
Carefully remove the tin from the oven and, working quickly, pour the batter around the pigs in blankets. Return to the oven and bake for 25 mins without opening the oven door. When the toad in the hole is ready, it should be puffed up and deep golden brown. If you prefer it darker brown, bake for 5 mins more. Serve with gravy and a medley of vegetables.
To make the gravy, melt the butter in a pan and add the flour. Cook for 1-2 minutes stirring until flour is cooked out. Stir in the wine and bring to the boil so it thickens and whisk out any lumps. Add the stock, redcurrant jelly, mushroom ketchup (If you haven’t got this you can use Worcester sauce instead) and mustard. Bring back to a simmer and season with salt and freshly ground pepper.