Heat the oil in a heatproof casserole over a high heat and brown the lamb shanks all over, until evenly coloured.
Add the carrot, onion, peppercorns, garlic and herbs.
Pour over enough wine to cover the meat of the shanks - about a whole bottle - then set the casserole aside to cool. Chill in the fridge overnight. (This helps to tenderise the meat.)
The next day, preheat the oven to 160C/325F/Gas 3. Place the casserole, covered with a lid, into the oven and cook for 2-2½ hours, or until the meat is tender. Slightly uncover the pot for the last hour so that the liquid will start to reduce. If the simmering becomes too lively during cooking, reduce the temperature slightly.
Remove the casserole from the oven. Remove the shanks from the cooking liquid and place in a roasting dish. Spoon over a couple of ladles of the cooking liquid to keep the shanks moist. Reserve the remaining cooking liquid. Roast the shanks in the oven for 45-60 minutes, or until the meat is falling off the bone.
Remove the vegetables from the cooking liquid with a slotted spoon or strain the liquid through a sieve.
Heat the cooking liquid until boiling, then boil until the volume has reduced by half. Stir in the redcurrant jelly until melted.
Serve the lamb shanks and reserved vegetables (from the cooking liquid) with mashed potatoes, seasonal vegetables and the gravy.