Combine the first 5 ingredients in a pot. Place over medium-high heat and bring to a boil, stirring to dissolve the sugar. While this occurs, peel and core the pears. (A melon baller works well to core the pear from its blossom end). Trim a little from the bottom of the pears so they will stand up straight. Add pears to the port mixture. Adjust the heat to a gentle simmer. Cover and cook until pears are just tender, about 15 minutes. Remove from heat. Cool the pears to room temperature in the port mixture, turning them over from time to time. Store the pears in the port mixture in the fridge until ready to serve.Using a slotted spoon, transfer pears to small serving plates, standing them up. Place wedges of stilton and walnuts alongside. If desired, serve with crackers and top with cheese, slices of pear and walnuts.