Exhibit 2.1

AMENDMENT NO. 1

TO THE

AGREEMENT AND PLAN OF MERGER

This AMENDMENT NO. 1 (this “Amendment”), dated as of March 19, 2012, to the Agreement and Plan of Merger, dated as of November 17, 2011 (the “Merger Agreement”), by and among MeadWestvaco Corporation, a Delaware corporation (“MWV”), Monaco SpinCo Inc., a Delaware corporation (“Spinco”), ACCO Brands Corporation, a Delaware corporation (the “Company”), and Augusta Acquisition Sub, Inc., a Delaware corporation and wholly owned Subsidiary of the Company (“Merger Sub”).

WHEREAS, the parties hereto are parties to the Merger Agreement;

WHEREAS, in connection with the transactions contemplated by the Transaction Agreements, the parties intend that Mead Products LLC, a direct, wholly owned Subsidiary of the Company (“Mead Products”), and the Surviving Corporation shall enter into an agreement and plan of merger (the “LLC Merger Agreement”), pursuant to which immediately after the Effective Time, the parties thereto will effect the merger of the Surviving Corporation with and into Mead Products (the “LLC Merger”), with Mead Products continuing as the surviving entity, all upon the terms and subject to the conditions to be set forth in the LLC Merger Agreement;

WHEREAS, the parties hereto desire to amend the Merger Agreement as set forth herein; and

WHEREAS, Section 10.4 of the Merger Agreement provides for the amendment of the Merger Agreement in accordance with the terms set forth therein.

NOW, THEREFORE, in consideration of the representations, warranties, covenants and agreements contained in this Amendment, and subject to the conditions set forth herein, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.1 Definitions; References. Unless otherwise specifically defined herein, each term used herein, including the Recitals hereto, shall have the meaning assigned to such term in the Merger Agreement as amended by this Amendment. Each reference in the Merger Agreement to “hereof,” “herein,” “hereunder,” “hereby” and “this Agreement” shall, from and after the date hereof, refer to the Merger Agreement as amended by this Amendment except that references to “the date hereof” and to “the date of this Agreement” shall remain references to the date of the original Merger Agreement.

ARTICLE II

AMENDMENTS TO MERGER AGREEMENT

Section 2.1 Amendments to Merger Agreement. The Merger Agreement shall be amended as follows:

WHEREAS, (i) concurrently with the execution of this Agreement, MWV and Spinco entered into the Separation Agreement in the form attached hereto as Exhibit A, which was subsequently amended by that Amendment No. 1 to the Separation Agreement, dated March 19, 2012 (as amended, the “Separation Agreement”), pursuant to which MWV will transfer or cause to be transferred to Spinco or one or more Spinco Subsidiaries all of the Spinco Assets, Spinco or one or more Spinco Subsidiaries will assume or cause to be assumed all of the Spinco Liabilities, and Spinco will issue Spinco Common Stock to MWV and pay the Special Dividend to MWV, all upon the terms and subject to the conditions set forth in the Separation Agreement (the “Spinco Reorganization”), and (ii) in connection with the transactions contemplated by the Transaction Agreements, the Company intends to cause Mead Products LLC, a direct, wholly owned Subsidiary of the Company (“Mead Products”), to enter into an agreement and plan of merger with the Surviving Corporation (the “LLC Merger Agreement”) pursuant to which immediately after the Effective Time, the parties thereto will effect the merger of the

Surviving Corporation with and into Mead Products (the “LLC Merger”), with Mead Products continuing as the surviving entity, all upon the terms and subject to the conditions to be set forth in the LLC Merger Agreement;

WHEREAS, the parties to this Agreement intend that, for U.S. federal income tax purposes, the Spinco Reorganization and Distribution, taken together, will qualify as a reorganization within the meaning of Section 368(a)(1)(D) of the Internal Revenue Code of 1986, as amended (the “Code”), and that the Merger and the LLC Merger, taken together, will qualify as a reorganization within the meaning of Section 368(a) of the Code.

“LLC Merger” shall have the meaning set forth in the Recitals hereto.

“LLC Merger Agreement” shall have the meaning set forth in the Recitals hereto.

“Mead Products LLC” shall have the meaning set forth in the Recitals hereto.

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Section 8.25 Company Stock Option Exercise Prohibition. On or prior to the date that is three (3) Business Days prior to the record date of the Distribution, the Company shall prohibit the holders of options to purchase Company Common Stock pursuant to the Company Stock Plan from exercising such options until after the Closing and shall instruct the Company’s transfer and other agent to prohibit the holders of options to purchase Company Common Stock pursuant to the Company Stock Plan from exercising such options until after the Closing. MWV shall give the Company written notice of the record date of the Distribution at least two (2) Business Days prior to the establishment of such record date.

Section 8.30. LLC Merger. Immediately following the Effective Time, the Company shall cause the Surviving Corporation to be merged with and into Mead Products in accordance with the applicable provisions of the Delaware Limited Liability Company Act and the DGCL.

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ARTICLE III

MISCELLANEOUS

Section 3.1 No Further Amendment. Except as expressly amended hereby, the Merger Agreement is in all respects ratified and confirmed and all the terms, conditions, and provisions thereof shall remain in full force and effect. This Amendment is limited precisely as written and shall not be deemed to be an amendment to any other term or condition of the Merger Agreement or any of the documents referred to therein.

Section 3.2 Effect of Amendment. This Amendment shall form a part of the Merger Agreement for all purposes, and each party thereto and hereto shall be bound hereby. From and after the execution of this Amendment by the parties hereto, any reference to the Merger Agreement shall be deemed a reference to the Merger Agreement as amended hereby.

Section 3.3 Governing Law. This Amendment shall be governed by, and construed in accordance with, the laws of the State of Delaware without giving effect to the conflicts of law principles thereof.

Section 3.4 Miscellaneous. Sections 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 11.11, 11.12 and 11.13 of the Merger Agreement shall apply to this Amendment mutatis mutandis.

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IN WITNESS WHEREOF, MWV, Spinco, the Company and Merger Sub have caused this Amendment to be signed by their respective officers hereunto duly authorized, all as of the date first written above