Preheat Oven to 325 F, with rack in center of oven. Generously grease a 9-inch (7-cup capacity) loaf pan. Dust with flour; tap pan over sink to discard excess flour. Cut piece of parchment paper or waxed paper to fit bottom of pan. Set aside.
For cake: use mixer to cream butter, sugar and vanilla until fluffy. Add eggs, 1 at a time, beating each until fluffy. Add cream cheese. Mix until well combined. Sift flour, baking powder and salt together. Put currants in small bowl. Add 1/4 cup of flour mixture to currants. Stir currants until well coated.
Add remaining flour to batter, alternating with buttermilk. Mix until smooth. Use wooden spoon to stir in currants and all of the flour. Stir until well combined. Transfer batter to prepared pan.
Smooth surface with spatula. Bake until well-browned and toothpick inserted into center comes out clean, about 1 hour, 25 minutes. Cake will crack on top. Let cake rest in pan for 10 minutes.
Use flexible metal spatula to separate cake from sides of pan. Carefully remove cake from pan to cooling rack. Spread glaze on warm cake.
Let cake cool completely. Cake can be stored 3 days at room temperature in foil. Cake can also be frozen up to 3 months, wrapped airtight.
For Glaze: combine sugar and lemon juice in small bowl. Stir until smooth.
