EXHIBIT 23.6

 
                                      Oppenheimer Tower
Oppenheimer & Co., Inc.               World Financial Center
                                      New York, New York 10281
                                      (212) 667-7000
 
 
Investment Banking Group


     We hereby consent to the inclusion of our opinion letter to the Board of
Directors of SIS Bancorp, Inc. as an Annex to the Proxy Statement/Prospectus
which forms a part of the Registration Statement on Form S-4 relating to the
proposed transactions among SIS Bancorp, Inc. and Glastonbury Bank & Trust
Company; and to the references to such opinion in such Proxy
Statement/Prospectus under the captions "Summary--Our Reasons for the Merger,"
"Summary--Opinions of Financial Advisers," "The Merger--Background of the
Merger," "The Merger--Recommendation of the SIS Board and Reasons for the
Merger" and "The Merger--Opinions of Financial Advisers."  In giving such
consent, we do not admit (i) that we come within the category of persons whose
consent is required under Section 7 of the Securities Act of 1933, as amended
(the "Securities Act"), or the rules and regulations of the Securities and
Exchange Commission promulgated thereunder, or (ii) that we are experts with
respect to any part of such Registration Statement within the meaning of the
term "experts" as used in the Securities Act or the rules and regulations of the
Securities and Exchange Commission promulgated thereunder.

                                     Oppenheimer & Co., Inc.
 
                                     By: /s/Mary Anne Callahan
                                        ---------------------------------
                                         Mary Anne Callahan
 
 
New York, New York
October 24, 1997