Mix together the tahini, mustard, honey, mustard seeds and sesame seeds. Combine 2 teaspoons of this paste with the chopped tarragon and spread the mixture over the concave inside of the racks.

Pre-heat the oven to 230.C (450.F or gas mark 8). Assemble the guard by interlocking the exposed rib bone tips. Using string tie the racks together. To prevent charring during cooking, cover the exposed bone tips with a single layer of aluminium foil, pressing the foil around the bones.

Roast the lamb for 50 minutes to 1 hour and 10 mins for rare to medium meat. Transfer the guard to a warm platter, cut away the strings, and set it aside to rest in a warm place.

To make the gravy, skim off the fat from the liquid in the roasting pan and transfer the pan to the stove top. Add the wine and boil it over high heat, stirring to scrape up any sediment from the bottom of the pan. Add the stock, tarragon, honey and salt and boil to reduce the liquid by about half. Strain the gravy into a sauce boat. Carve the guard at the table.