From the The New Doubleday Cookbook which is not really new having last been updated in 1985 to the best of my knowledge. However, that is of little account as it remains my "go to" book for the basics.
Yields 2-1/2 cups.
1 cup mayonnaise
1 tablespoon sugar
1 teaspoon prepared mild yellow mustard
1/2 teaspoon prepared horseradish
1/2 teaspoon Worcestershire sauce
1/2 teaspoon minced garlic
1 tablespoon grated onion
1/2 pound Roquefort cheese (I use Maytag Blue ... I know, I know, it isn't a true Roquefort, so sue me)
3-4 tablespoons cider vinegar
Blend mayonnaise with sugar, mustard, horseradish, Worcestershire sauce, garlic, and onion. Crumble in Roquefort and stir well. Mix in 3-4 tablespoons vinegar, depending upon how thick a dressing you want.