1 --------------------------- ----------------- CUSIP No. 441560109 13G Page 7 of 8 Pages --------------------------- ----------------- EXHIBIT 1 TO SCHEDULE 13G February 14, 1997 MORGAN STANLEY GROUP INC. and MORGAN STANLEY ASSET MANAGEMENT LIMITED...

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CUSIP No.   ▇▇▇▇▇▇▇▇▇               13G                       Page 7 of 8 Pages
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                           EXHIBIT 1 TO SCHEDULE 13G


                               February 14, 1997



       ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ GROUP INC. and ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ASSET MANAGEMENT LIMITED
     hereby agree that, unless differentiated, this Schedule 13G is filed on
     behalf of each of the parties.


       ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ASSET MANAGEMENT LIMITED

   BY: /s/ ▇▇▇▇▇ ▇. ▇▇▇▇▇▇
       ------------------------------------------------------------------------
       ▇▇▇▇▇ ▇. ▇▇▇▇▇▇/Director ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Asset Management Limited
                                    



       ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ GROUP INC.

   BY: /s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
       ------------------------------------------------------------------------
       ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇/Vice President ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ & Co. Incorporated