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                                                                     EXHIBIT 4.2

                       [Union Electric Company Letterhead]

                                  COMPANY ORDER

                                                         May [  ], 2002

The Bank of New York
[101 Barclay Street
Floor 21W
New York, New York 10286]

Ladies and Gentlemen:

     Application is hereby made to The Bank of New York, a New York banking
corporation, as trustee (the "Trustee"), under the Indenture dated as of May
[  ], 2002 (the "Indenture"), between Union Electric Company, a Missouri
corporation (the "Company"), and the Trustee for the authentication and delivery
of $[     ] aggregate principal amount of the Company's [  ]% Senior Notes due
[  ] (the "Notes"), pursuant to the provisions of Article II of the Indenture.
All capitalized terms not defined herein which are defined in the Indenture
shall have the same meaning as used in the Indenture.

     In connection with this Company Order, there are delivered to you herewith
the following:

     1. Certified copies of the resolutions adopted by the Board of Directors of
        the Company [and by the Executive Committee of the Board of Directors of
        the Company] authorizing this Company Order and the issuance and sale of
        the Notes by the Company pursuant to Section 2.05(c)(1) of the
        Indenture;

     2. Opinions of Counsel addressed to you or in which it is stated that you
        may rely pursuant to Section 2.05(c)(2) of the Indenture;

     3. Expert's certificate pursuant to Section 2.05(c)(3) of the Indenture;

     4. Officers' Certificate pursuant to Section 2.05(c)(4) of the Indenture;

     5. A Global Note representing the Notes and, pursuant to Section 2.05(c) of
        the Indenture, specifying the terms of the Notes (which terms are
        incorporated by reference herein) executed on behalf of the Company in
        accordance with the terms of Section 2.05(a) of the Indenture; and

     6. Pursuant to Section 2.05(c)(3) of the Indenture, the Company's First
        Mortgage Bonds designated "First Mortgage Bonds, Senior Notes Series
        [  ]" in the principal amount of $[     ] relating to the Notes, fully
        registered in the name of the Trustee in trust for the benefit of the
        Holders from time to time of such Notes.

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     You are hereby instructed to authenticate the Global Note representing the
Notes and deliver it to The Depository Trust Company ("DTC") or its custodian.
The Global Note representing the Notes is to be held for delivery to Banc of
America Securities LLC, on behalf of the several underwriters, against payment
therefor at the closing in respect of the sale thereof, such closing to be held
at 10:00 a.m., New York time, [   ], 2002, at the offices of Pillsbury Winthrop
LLP, One Battery Park Plaza, New York, NY 10004.

     Please acknowledge receipt of the Global Note representing the Notes, the
instructions referred to above and the supporting documentation pursuant to the
Indenture referred to above.

                                           Very truly yours,

                                           Union Electric Company
                                           (d/b/a AmerenUE)

                                           By:
                                              --------------------------
                                              Name:
                                              Title:

     Receipt from the Company of the Global Note representing the Notes, certain
instructions related thereto and the supporting documentation pursuant to the
Indenture in connection with the authentication and delivery of the Notes is
hereby acknowledged.

                                           The Bank of New York,
                                           as Trustee

                                           By:
                                              ---------------------------
                                              Name:
                                              Title:

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