Place potatoes, parsnips and celeriac into a large saucepan of cold water. Bring to the boil and simmer until vegetables are tender.

Heat oil in large saucepan and add onion and thyme, and cook gently until soft and starting to brown.

Add splash of ale, stock, gravy granules and simmer to achieve your desired thickness of gravy (Add a pinch of sugar if it’s a little bitter).

Place sausages under a pre-heated grill and cook for about 10 minutes until browned and cooked through.

Drain root vegetables and mash together with butter and seasoning.