Preheat the oven to 425°F

Remove the lamb from the refrigerator and allow to sit on the workspace for 30 minutes.

Trim the lamb of as much of the silvery membrane and excess fat but leave a layer of fat on top of the lamb as it will add flavor and a rich crisp crust. Also remove the flesh off the bone end at the last three inches to expose the end of the bone.

In a small bowl, blend together the garlic, anchovy paste, rosemary, olive oil, lemon juice, salt, pepper, and lemon zest.  

Spread part of the mixture evenly over the underside of the lamb and place fat side up on a wire rack set over a rimmed baking sheet. Spread the remaining mixture over the upper fat side of the leg. Insert a meat probe into the thickest part of the lamb ensuring that it does not touch the bone. 

Pull of a large sheet of aluminum foil and squish it into a firm ball. Place the foil-ball under the bone end to elevate the end. This will allow more uniform circulation and even heating.

Add the beef broth and the wine to the pan and transfer to the oven.  Roast for 20-minutes then reduce the oven temperature to 325°F and continue to roast until the meat probe reaches the desired doneness. For medium rare 130° to 135°F. it will be about 1-hour.

Remove the roasted lamb to a workspace and transfer the lamb to a platter, tent loosely with foil and allow to rest for a minimum of 20 minutes before carving.

Remove the wire rack from the baking pan and place the pan on the stove top to fit over two burners set at medium-high. Add 1 cup of the beef broth to deglaze the pan. Scrape up all bits that are stuck to the bottom of the pan. Carefully transfer the drippings to a saucepan and spoon off the excess fat that rises to the top.

Add the remaining beef broth, red wine and Worcestershire sauce to the saucepan, adjust the salt and pepper to taste. Bring to a boil then reduce the heat to it’s lowest heat.

There should be about 2 cups of liquid for the gravy. In a small dish, add 2 tablespoons of soft butter and 2 tablespoons flour and mash together with the back of a spoon until a paste forms. Whisk the flour/butter paste into the simmering liquid and cook for another minute to thicken slightly.  

Transfer the gravy to a pitcher or dish and serve with the lamb.