EXHIBIT 23.7 CONSENT OF INDEPENDENT CERTIFIED PUBLIC ACCOUNTANTS --------------------------------------------------- We consent to the incorporation by reference in this Registration Statement on Form S-4 (File No. 33-57033) our report dated January 15, 1994, appearing in the Westamerica Registration Statement on Form S-4 (File No. 33-55417) filed on October 5, 1994 with the Securities and Exchange Commission pursuant to the Securities Act of 1933. /s/ Grant Thornton Stockton, California January 27, 1995