Heat the olive oil in a large, wide pan with a lid over a medium heat. Season the lamb shanks and brown in the pan for 8-10 minutes. Remove and set on a plate while you add the onion and carrot to the pan and cook for 8 minutes, stirring, until golden brown. Add the bay leaves, rosemary, garlic, thyme and return the shanks to the pan. Pour in the stock and red wine and heat until just bubbling. Cover with a tight-fitting lid and bake for 3 hours, until the meat is tender.
To make the champ, peel and quarter the potatoes. Place them in a large pan, cover with salted water and bring to the boil. Simmer until just cooked. While the potatoes are cooking, wash and finely chop the spring onions. Combine the milk and butter in a small pan and bring to the boil.
Put the chopped scallions into the boiling mixture, then remove from the heat and let them infuse. They will soften and flavour the milk. Drain the potatoes, cover the pan and let it sit for about 2 minutes. Mash the potatoes, stir in the milk and scallions until smooth and creamy. Taste and add salt if necessary.
Transfer the shanks to a dish, cover loosely with foil and rest while you make the sauce. Skim off and discard the fat from the surface of the liquid, strain and discard the vegetables and herbs. Bring the sauce to the boil, reduce the temperature and simmer for a few minutes until thickened, finally add the chopped parsley and redcurrant jelly.
Divide the lamb shanks between 4 serving plates, spoon over the red wine sauce and serve with creamy champ and roasted cherry tomatoes.