Exhibit 21 CERTAIN SUBSIDIARIES OF MARKEL CORPORATION State or Other Jurisdiction of Incorporation or Subsidiary Organization - ---------------------------------------------------- ---------------- Essex Insurance Company Delaware Markel Insurance Company Illinois Markel American Insurance Company Virginia Shand/Evanston Group, Inc. Virginia Evanston Insurance Company Illinois Gryphon Holding Inc. Delaware Associated International Insurance Company California Terra Nova (Bermuda) Holdings Ltd. Bermuda Markel International Limited England Markel International Insurance Company Limited England Terra Nova (Bermuda) Insurance Company Ltd. Bermuda Markel Capital Limited England