Trim excess fat from lamb. Cut 6 large incisions into the lamb,rub the lamb all over with the cut garlic. Insert the rosemary sprigs into the incisions. Brush the lamb well with redcurrant jelly and season with sea salt & ground pepper.
Leaving the skin on the pumpkin, remove the seeds and cut into 2 inch wedges. Peel the onion and cut into rounds, but don't separate the rings. Cut any large potatoes into half.
Place the potatoes, pumpkin, onions and bay leaf in a 22 cup(192 fl oz) slow cooker, than rest the lamb on top.
Cover and cook for 8 hours.
Remove lamb from slow cooker and put on a warming plate. Cover with foil and leave to rest in a warm place for 10 minutes before serving.
Drizzle veggies in the slow cooker with the olive oil and seasoning.
Carve the lamb and serve with the remaining redcurrant jelly, the braised veg and steamed peas.
I use seasonal veg. What ever is growing in the garden. eg. Beetroot, carrots or turnip as well as the potatoes, pumpkin etc. Sweet potatoes (red or white) are really nice, you can leave the skin on but wash well.