Preheat the oven to Gas mark 4-5, 180-190°C, 350-375°F.
To prepare the stuffing; drain the dates, reserving the orange liqueur and transfer to a small bowl. Add the remaining stuffing ingredients.
Place the lamb on a chopping board, season and sprinkle with the cinnamon on both sides.
Heat the oil in a non-stick frying pan, add the lamb, skin side down and cook for 1-2 minutes on each side until brown. Remove and place on a clean chopping board.
Fill the cavity of each rack with the stuffing mixture and sandwich together to form an arch. Secure with butcher’s string or elasticated meat bands.
Weigh the racks, transfer to a medium-sized roasting tin and roast for the calculated cooking time (for medium). Cover the bones with foil if browning too quickly.
In a small bowl mix together 2tbsp of the reserved orange liqueur and the marmalade.
10 minutes before the end of the cooking time brush the racks with the marmalade glaze. Remove from the oven and set aside to rest for 5 minutes.
Slice the Guard of Honour and serve with mini roast potatoes and seasonal vegetables.