Lay the pork on a board, flesh side up. Make incisions all over with a sharp knife and fill with the slivers of garlic. Rub the fennel and rosemary all over the flesh, along with olive oil to lubricate, pushing bits down inside the slits, and season generously.
Make a bed in a roasting tin with rosemary sprigs and the bay leaves and lay on the pork, fat side down. Cover and chill overnight. Bring to room temperature before cooking.
Preheat the oven to 220°C/425°F/gas mark 7. Tie the loin at intervals with kitchen string (not too tightly; it should hold its shape but not look like a sausage). Put into the roasting tin fat side up on top of the herbs (make sure these are under the pork or they will scorch) and cook for 25 minutes. Reduce the oven temperature to 180°C/ 350°F/gas mark 4 and cook for 1 hour 40 minutes, basting every so often.
Check to make sure it is properly cooked; the juices should run clear with no trace of pink when the flesh is pierced. Take the pork out of the oven, cover with foil, insulate and allow to rest for 15-20 minutes. Serve hot or at room temperature.
Honey and mustard roast pork loin Lay the same-sized cut of pork as above on a board, flesh side up. Make incisions all over with a sharp knife. Stuff the chopped leaves from 3 rosemary sprigs into the incisions and season. Mix 4 tbsp Dijon mustard, 7 tbsp runny honey and the juice of ½ lemon and pour three quarters of it over the joint, making sure it goes down into the incisions. Refrigerate for a few hours, but bring to room temperature before cooking. Preheat the oven to 220°C/ 425°F /gas mark 7. Tie the loin with kitchen string as above. Put into a roasting tin with it's marinade. Cook as above, basting. Add the remaining honey and mustard mix 10 minutes before the end of the cooking time. If the joint is becoming too dark (if the honey begins to burn), cover with foil. When it is cooked, take it from the oven and cover with foil, insulate and rest for 15 minutes. Serve hot or at room temperature.
Food from Plenty by Diane Henry and Jonathan Lovekin, published by Mitchell Beazley: Good Food Made from the Plentiful, the Seasonal and the Leftover with Over 300 Recipes, None of Them Extravagant, . Order the book online.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.