June 5, 2000


Joseph E. Kasputys
Primark Corporation
1000 Winter Street
Suite 4300
Waltham, MA  02451


Dear Joe,

         The Thomson Corporation ("Thomson") hereby guarantees the performance
of the obligations of Primark Corporation under Section 5(b) of the Employment
Agreement dated January 7, 1997 between you and Primark Corporation.

         Thomson has all necessary power and authority to execute and deliver
this agreement, to perform its obligations hereunder and to consummate the
transaction contemplated hereby. The execution and delivery of this agreement by
Thomson and the consummation by Thomson of the transaction contemplated hereby
have been duly and validly authorized by all necessary corporate action and no
other corporate proceedings on the part of Thomson are necessary to authorize
this agreement or to consummate the transaction contemplated hereby. This
agreement has been duly executed and delivered by Thomson, and constitutes a
legal, valid and binding obligation of Thomson enforceable in accordance with
its terms.


                                             By: /s/ Michael S. Harris
                                                --------------------------------
                                                    THE THOMSON CORPORATION