Place the sausages in a large non-stick casserole pan on a medium-high heat with 1 tablespoon of olive oil and brown for 10 minutes, turning regularly, then remove to a plate, leaving the pan on the heat.

Meanwhile, peel the potatoes, chop into even-sized chunks and cook in a large pan of boiling salted water for 15 minutes, or until tender, then drain and leave to steam dry.

Mash well with half the mustard, then season to perfection.

Trim, wash and chop the carrots and leeks into 2cm chunks.

Stir into the fat in the pan and cook for 15 minutes, or until softened, stirring regularly, and adding a splash of water, if needed.

Stir the HP sauce and remaining mustard into the veg, then pour in the beans, juice and all.

Add the tomatoes, breaking them up with the spoon, then stir in 1 tin’s worth of water.

Bring to the boil and cook for another 10 minutes, then season to perfection.

Preheat the grill to high.

Score the sausages at ½cm intervals and sit them cut side up in the stew.

As soon as the mash is cool enough to handle, divide it into four compact balls, push them into the stew and brush with 2 tablespoons of oil.

Grill on the top shelf of the oven for 15 minutes, or until golden and bubbling.