Trim the crusts from the load of bread and cut into dozen slices 0 cm thick. In a small bowl, mash together the chopped anchovies, butter, mustard, eggs, herbs and pepper. The mixture should be quite smooth. Thickly spread it on 6 slices of bread. Top each slice with another piece of bread and lightly press them together. At this point, the sandwiches may be wrapped in wax paper and refrigerated for up to 3 days or even frozen (they should be thoroughly defrosted before using). Over moderate heat, melt the butter and oil in a 10-12 inch skillet. When the foam subsides, add the sanwiches, 2 or 3 at a time, and fry for 2 to 3 minutes on each side until they are crisp and golden brown. Drain on paper towels and serve while hot either whole as a main luncheon course or snack, or cut in quarters to accompany cocktails. Makes 6 sandwiches or 24 hors d'oeurve