(From "Mark Peel and Nancy Silverton at Home," Warner.) To prepare port wine syrup: in a shallow pan combine port with rest of ingredients, except berries. Bring to a boil over high heat and reduce to 1 cup, which will take about 20 minutes. Remove from heat and let stand for 15 minutes. Strain into medium bowl. Add half boysenberries and raspberries and crush fruit with the back of a large spoon. Stir in remaining berries, except strawberries. Cover and chill for 2-3 hours or overnight. Just before serving, slice strawberries and stir them into fruit mixture. Spoon into glass bowls or goblets. To prepare fool: reserve several perfect straberries for garnish. Hull remaining berries, slice through the stem end, and place in a nonreactive bowl. Pour warm syrup through strainer over berries, crushing fruit gently with a fork. Set aside for 30 minutes at room temperature or 1 hour in refrigerator. When ready to serve, beat heavy cream to soft peaks and mix in sour cream. Remove berries from liquid with slotted spoon and carefully fold them into cream. Spoon a small puddle of Port Wine Syrup onto individual dessert plates or into wine goblets and top with cream and berries. Drizzle a little syrup over cream and garnish with reserved strawberries.