Preheat the oven to 400 degrees F.
Toast the bread for about 5 minutes then set aside to cool. Combine the watercress, buttermilk dressing and cream cheese in a food processor or blender and puree. Spread the toast with the cream cheese mixture. Shingle cucumbers on top of each slice of bread then cut the sandwiches into triangles. Arrange the sandwiches on 4 plates, garnish with red pepper and serve.