Exhibit
      10.11

     

    GHL
      ACQUISITION CORP.

     

    UNIT
      CANCELLATION AGREEMENT AND AMENDMENT TO FOUNDER’S SECURITIES PURCHASE
      AGREEMENT

     

    THIS
      UNIT
      CANCELLATION AGREEMENT AND AMENDMENT TO FOUNDER’S SECURITIES PURCHASE AGREEMENT
      (this “Agreement”), dated as of January 10, 2008, is entered
      into by and between GHL Acquisition Corp., a Delaware corporation (the
“Corporation”), and Greenhill & Co., Inc., a Delaware
      corporation (the “Founding Stockholder”).

     

    WITNESSETH

     

    WHEREAS,
      the Corporation has filed a registration statement for its initial public
      offering of units (the “IPO”), each unit (a
“Unit”) consisting of one Share of the Corporation’s common
      stock, par value $0.001 per share (a “Share”) and one warrant
      to purchase one Share;

     

    WHEREAS,
      the Founding Stockholder purchased an aggregate of 11,500,000 Units (the
“Founder’s Units”) pursuant to a Founder’s Securities Purchase
      Agreement (the “Purchase Agreement”), dated as of November 12,
      2007, between the Corporation and the Founding Stockholder, of which Founder’s
      Units 1,500,000 Founder’s Units are subject to forfeiture under certain
      circumstances pursuant to the terms of the Purchase Agreement;

     

    WHEREAS,
      the Corporation wishes to amend the terms of the IPO such that the Shares
      included in the Units being sold to the public represent approximately 82.5%
      of
      the Corporation’s outstanding share capital following consummation of the
      IPO;

     

    WHEREAS,
      the Founding Stockholder believes it is in the best interests of it, the
      Corporation and the Corporation’s shareholders to proceed with the IPO on the
      amended terms, and wishes to facilitate this by surrendering 1,725,000 Founder’s
      Units (the “Subject Units”) to the Corporation for cancellation
      on the terms and conditions set forth herein;

     

    NOW
      THEREFORE, in consideration of the mutual promises contained in this Agreement
      and other good and valuable consideration, the receipt and sufficiency of which
      are hereby acknowledged, the parties to this Agreement hereby agree as
      follows:

     

    Section
      1.  Surrender
      and Cancellation

     

    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    

     

    The
      Founding Stockholder hereby surrenders to the Corporation, and the Corporation
      hereby accepts from the Founding Stockholder, free and clear of all liens and
      encumbrances, the Subject Units.  The Corporation shall duly cancel
      and retire the Subject Units as promptly as practicable.  Of the
      9,775,000 Founder’s Units remaining after giving effect to the surrender and
      cancellation of the Subject Units, 1,275,000 Founder’s Units, subject to
      adjustment, are subject to forfeiture pursuant to the terms of the Purchase
      Agreement (as amended by this Agreement).

     

    Section
      2.  Representations
      and Warranties of the Founding Stockholder.  The Founding
      Stockholder hereby represents and warrants that:

     

    (A)  Organization
      and Corporate Power.  The Founding Stockholder is a corporation
      duly organized, validly existing and in good standing under the laws of the
      State of Delaware. The Founding Stockholder possesses all requisite corporate
      power and authority necessary to carry out the transactions contemplated by
      this
      Agreement.

     

    (B)  Authorization;
      No Breach.

     

    (i)  The
      execution, delivery and performance of this Agreement have been duly authorized
      by the Founding Stockholder. This Agreement constitutes a valid and binding
      obligation of the Founding Stockholder, enforceable in accordance with its
      terms.

     

    (ii)  The
      execution and delivery by the Founding Stockholder of this Agreement, the
      surrender of the Subject Units and the fulfillment of and compliance with the
      respective terms hereof by the Founding Stockholder, do not and will not as
      of
      the date hereof (i) conflict with or result in a breach of the terms, conditions
      or provisions of, (ii) constitute a default under, (iii) result in a violation
      of, or (iv) require any authorization, consent, approval, exemption or other
      action by or notice or declaration to, or filing with, any court or
      administrative or governmental body or agency pursuant to the certificate of
      incorporation or by-laws of the Founding Stockholder, or any material law,
      statute, rule or regulation to which the Founding Stockholder is subject, or
      any
      agreement, order, judgment or decree to which the Founding Stockholder is
      subject, except for any filings required after the date hereof under federal
      or
      state securities laws.

     

    (C)  Title
      to Units.  The Founding Stockholder is the sole record owner of
      the Subject Units and has the power and right to surrender, assign, transfer
      and
      deliver to the Corporation good and valid title to, all of the Subject Units,
      free and clear of all liens.

     

    
      
        
        

      

      
        2

        
          

        

      

      
        
        

      

    

     

    Section
      3.  Representations,
      Warranties and Covenants of the Corporation.  As a material
      inducement to the Founding Stockholder to enter into this Agreement and
      surrender the Subject Units to the Corporation, the Corporation hereby
      represents, warrants and covenants to the Founding Stockholder
      that:

     

    (A)  Organization
      and Corporate Power.  The Corporation is a corporation duly
      organized, validly existing and in good standing under the laws of the State
      of
      Delaware. The Corporation possesses all requisite corporate power and authority
      necessary to carry out the transactions contemplated by this
      Agreement.

     

    (B)  Authorization;
      No Breach.

     

    (i)  This
      Agreement constitutes a valid and binding obligation of the Corporation,
      enforceable in accordance with its terms.

     

    (ii)  The
      execution and delivery by the Corporation of this Agreement and the fulfillment
      of and compliance with the respective terms hereof by the Corporation do not
      and
      shall not as of the date hereof conflict with or result in a breach of the
      terms, conditions or provisions of any agreement, instrument, order, judgment
      or
      decree to which the Corporation is subject.

     

    Section
      4.  Amendment
      of Purchase Agreement.  The Founding Stockholder and the
      Corporation hereby acknowledge and agree that clauses (a) and (b) of Section
      1.C.vii. of the Purchase Agreement are amended and restated by deleting such
      clauses in their entirety and replacing them with the following
      text:

     

    (A)  “(a)  If
      the underwriters with respect to the Initial Public Offering do not exercise
      the
      over-allotment option proposed to be granted to them by the Company, the
      Purchaser and any Permitted Transferees agree to forfeit to the Company a number
      of Founder’s Units necessary to ensure that the aggregate amount of Founder’s
      Shares held by the Purchaser and any Permitted Transferees does not exceed
      approximately 17.5% of the issued and outstanding common stock of the Company
      upon consummation of the Initial Public Offering.  The Purchaser and
      any Permitted Transferees agree to take any and all action reasonably requested
      by the Company necessary to effect any adjustment pursuant to this paragraph
      vii(a), and agree that the exact number of Founder’s Units forfeited to effect
      any such adjustment shall be determined by the Company in its sole
      discretion.  The Company will not make any cash payment to the
      Purchaser or any Permitted Transferees in respect of any such
      adjustment.”

     

    (B)  “(b)  If
      the number of units offered to the public in connection with the Initial Public
      Offering is increased or decreased, the Purchaser and any

     

    
      
        
        

      

      
        3

        
          

        

      

      
        
        

      

    

     

    Permitted
      Transferees agree with the Company and the Company hereby agrees with the
      Purchaser and any Permitted Transferees that the Founder’s Units (including the
      Founder’s Units subject to forfeiture) will be adjusted in the same proportion
      as the increase or decrease of the units offered to the public in order to
      ensure that the aggregate amount of Founder’s Shares held by the Purchaser and
      any Permitted Transferees does not fall below or exceed approximately 17.5%
      of
      the issued and outstanding common stock of the Company upon consummation of
      the
      Initial Public Offering (including any shares of common stock issued pursuant
      to
      the underwriters’ over-allotment option).  The Purchaser and any
      Permitted Transferees agree to take any and all action reasonably requested
      by
      the Company necessary to effect any adjustment pursuant to this paragraph
      vii(b), and agree that the exact number of Founder’s Units forfeited to effect
      any such adjustment shall be determined by the Company in its sole discretion;
      provided that the Company will not make or receive any cash payment to
      or from the Purchaser or any Permitted Transferees in respect of any such
      adjustment.”

     

    Section
      5.  Survival
      of Representations and Warranties.  All of the representations
      and warranties contained herein shall survive the date of this
      Agreement.

     

    Section
      6.  Miscellaneous.

     

    (A)  Successors
      and Assigns.  Except as otherwise expressly provided herein, all
      covenants and agreements contained in this Agreement by or on behalf of any
      of
      the parties hereto shall bind and inure to the benefit of the respective
      successors of the parties hereto whether so expressed or not.

     

    (B)  Severability.  Whenever
      possible, each provision of this Agreement shall be interpreted in such manner
      as to be effective and valid under applicable law, but if any provision of
      this
      Agreement is held to be prohibited by or invalid under applicable law, such
      provision shall be ineffective only to the extent of such prohibition or
      invalidity, without invalidating the remainder of this Agreement.

     

    (C)  Counterparts.  This
      Agreement may be executed in counterparts, all of which taken together shall
      constitute one and the same Agreement.

     

    (D)  Descriptive
      Headings; Interpretation.  The descriptive headings of this
      Agreement are inserted for convenience only and do not constitute a substantive
      part of this Agreement. The use of the word “including” in this Agreement shall
      be by way of example rather than by limitation.

     

    (E)  Governing
      Law.  This Agreement shall be deemed to be a contract made under
      the laws of the State of New York and for all purposes shall be construed in
      accordance with the internal laws of said State. The parties agree that, all
      actions and proceedings arising out of this Agreement or any of the

     

    
      
        
        

      

      
        4

        
          

        

      

      
        
        

      

    

     

    transactions
      contemplated hereby, shall be brought in the United States District Court for
      the Southern District of New York or in a New York State Court in the County
      of
      New York and that, in connection with any such action or proceeding, agree
      to
      submit to the jurisdiction of, and venue in, such court. Each of the parties
      hereto also irrevocably waives all right to trial by jury in any action,
      proceeding or counterclaim arising out of this Agreement or the transactions
      contemplated hereby.

     

    (F)  Notices.  All
      notices, demands or other communications to be given or delivered under or
      by
      reason of the provisions of this Agreement shall be in writing and shall be
      deemed to have been given when delivered personally to the recipient, sent
      to
      the recipient by reputable overnight courier service (charges prepaid) or mailed
      to the recipient by certified or registered mail, return receipt requested
      and
      postage prepaid. Such notices, demands and other communications shall be
      sent:

     

    
      	
              If
                to the Corporation:

            	 	
              GHL
                Acquisition Corp.

              300
                Park Avenue, 23rd
                Floor

              New
                York, NY  10022

              Fax
                No.: (212)
                389-1700

            
	 	 	 
	
              With
                a copy to:

            	 	
              Deanna
                L. Kirkpatrick

              Davis
                Polk & Wardwell

              450
                Lexington Avenue

              New
                York, NY  10017

              Fax
                No.: 212-450-3135

            
	 	 	 
	
              If
                to the Founding Stockholder:

            	 	
              Greenhill
                & Co., Inc.

              300
                Park Avenue, 23rd
                Floor

              New
                York, NY  10022

              Fax
                No.: (212)
                389-1700 

            


    

    


    or
      to such
      other address or to the attention of such other person as the recipient party
      has specified by prior written notice to the sending party.

     

    (G)  No
      Strict Construction.  The parties hereto have participated
      jointly in the negotiation and drafting of this Agreement. In the event an
      ambiguity or question of intent or interpretation arises, this Agreement shall
      be construed as if drafted jointly by the parties hereto, and no presumption
      or
      burden of proof shall arise favoring or disfavoring any party by virtue of
      the
      authorship of any of the provisions of this Agreement.

     

    
      
        
        

      

      
        5

        
          

        

      

      
        
        

      

    

     

    IN
      WITNESS
      WHEREOF, the parties hereto have executed this Agreement and Amendment on
      the date first written above.

     

    


    
      	 	
              GHL
                ACQUISITION CORP.

            	 
	 	 	 	 
	 	 	 	 
	 	 	/s/
              Scott
              L. Bok	 
	 	
              By:

            	
              Scott
                L. Bok

              Chairman
                and Chief Executive Officer

            	 


    

     

    
      
        	 	
                
                  GREENHILL
                    & CO., INC.

                

              	 
	 	 	 	 
	 	 	 	 
	 	 	/s/
                Scott
                L. Bok	 
	 	
                By:

              	
                Scott
                  L. Bok

                Co-Chief
                  Executive Officer