Fry bacon in skillet until crisp. Remove and drain on paper towels. Crumble. Saute onion, celery, green pepper and mushrooms in bacon dripping until tender. Do not brown.
Combine soup and sour cream in a bowl. Add chicken, salt, Worcestershire sauce, pepper, 1 tablespoon milk, bacon, and sauteed vegetables; mix well. Turn into a 2 litre greased casserole.
Combine biscuit mix, eggs, half cup milk, pimentos, and cheese; mix until just blended. Drop by spoonfuls on top of chicken mixture.
Bake in moderate oven, 350 degrees, for 45 minutes or until biscuits are golden.
Makes 6-8 servings.