CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
    We consent to incorporation by reference in the Registration Statement on
Form S-4 of UST Corp. of our reports on the consolidated financial statements of
The Federal Savings Bank as of December 31, 1995 and 1994 and for each of the
years in the two-year period ended December 31, 1995 and on the consolidated
financial statements of Main Street Community Bancorp, Inc. as of and for the
year ended December 31, 1994, which reports appear in the Current Report on Form
8-K of UST Corp. dated February 6, 1998 and to the reference to our firm under
the heading "Experts" in the Registration Statement.
 
                                          KPMG PEAT MARWICK LLP
 
Boston, Massachusetts
February 6, 1998