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                                                                     EXHIBIT 4.2

[BMO NESBITT BURNS LETTERHEAD]

March 22, 2003

     We hereby consent to the inclusion of our opinion letter dated as of
February 14, 2003 to the Board of Directors of Canada Life Financial
Corporation ("Canada Life") as Schedule B to the Canada Life Financial
Corporation Management Proxy Circular which is a part of the Registration
Statement, dated March 22, 2003, on Form F-8 (the "Registration Statement")
of Great-West Lifeco Inc. (the "Company") in connection with the proposed
transaction involving the Company and Canada Life, and to the references
therein to our opinion contained under the headings "Summary of Proxy
Circular - Recommendation of the Special Committee and the Board", "Summary
of Proxy Circular - BMO Nesbitt Burns and CSFB Fairness Opinions", "The
Transaction - Background to the Transaction", "The Transaction - Reasons for
the Transaction" and "The Transaction - Fairness Opinions".

     In giving such consent, we do not admit that we come within the category
of persons whose consent is required under, nor do we admit that we are
"experts" for purposes of, the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.

Yours truly,

BMO NESBITT BURNS INC.

/s/ BMO Nesbitt Burns Inc.<Page>

                                                                     EXHIBIT 4.3

                      [Letterhead of McCarthy Tetrault LLP]

                                                    March 22, 2003

          RE: CONSENT OF LEGAL COUNSEL

          As independent Canadian legal counsel, we hereby consent to the use in
this Registration Statement on Form F-8 (the "Registration Statement") of
Great-West Lifeco Inc. (the "Company") relating to the issuance of common
shares, 4.80% Non-Cumulative First Preferred Shares, Series E and 5.90%
Non-Cumulative First Preferred Shares, Series F of the Company of our opinion
contained under the headings "Eligibility for Investment in Canada" and "Tax
Considerations for Canada Life Shareholders - Canadian Federal Income Tax
Considerations" in the Canada Life Financial Corporation Management Proxy
Circular, which is part of the Registration Statement.

          We further consent to all references to our firm included or
incorporated by reference in the Registration Statement.

                                   Very truly yours,

                                   /s/ McCarthy Tetrault LLP<Page>

                                                                     EXHIBIT 4.4

[LETTERHEAD OF LEBOEUF, LAMB, GREENE & MACRAE L.L.P.]

                                                     March 24, 2003

          RE: CONSENT OF LEGAL COUNSEL

          As independent United States legal counsel, we hereby consent to the
use in this Registration Statement on Form F-8 (the "Registration Statement") of
Great-West Lifeco Inc. (the "Company") relating to the issuance of common
shares, 4.80% Non-Cumulative First Preferred Shares, Series E and 5.90%
Non-Cumulative First Preferred Shares, Series F of the Company of our opinion
contained under the heading "Tax Considerations for Canada Life Shareholders -
United States Federal Income Tax Considerations" in the Canada Life Financial
Corporation Management Proxy Circular, which is part of the Registration
Statement.

          We further consent to all references to our firm included or
incorporated by reference in the Registration Statement.

                                  Very truly yours,

                                  /s/ LeBoeuf, Lamb, Greene & MacRae, L.L.P.<Page>

                                                                     EXHIBIT 4.5

                        [Letterhead of Slaughter and May]

                                                     March 25, 2003

Dear Sirs

CONSENT OF LEGAL COUNSEL

As independent United Kingdom legal counsel, we hereby consent to the use
in this Registration Statement on Form F-8 (the "Registration Statement") of
Great-West Lifeco Inc. (the "Company") relating to the issuance of common
shares, 4.80% Non-Cumulative First Preferred Shares, Series E and 5.90%
Non-Cumulative First Preferred Shares, Series F of the Company of our opinion
contained under the headings "Tax Considerations for Canada Life Shareholders -
United Kingdom Tax Considerations" in the Canada Life Financial Corporation
Management Proxy Circular dated 22 March 2003 (the "Circular"), which is part
of the Registration Statement.

We further consent to all references to our firm included in the Circular,
which forms part of the Registration Statement.

Yours faithfully

SLAUGHTER AND MAY

/s/ Slaughter and May<Page>

                                                                     EXHIBIT 4.6

                           [Letterhead of Arthur Cox]

                                                   March 22, 2003

          TO WHOM IT MAY CONCERN

          RE: CONSENT OF LEGAL COUNSEL

          As independent Irish legal counsel, we hereby consent to the use in
this Registration Statement on Form F-8 (the "Registration Statement") of
Great-West Lifeco Inc. (the "Company") relating to the issuance of common
shares, 4.80% Non-Cumulative First Preferred Shares, Series E and 5.90%
Non-Cumulative First Preferred Shares, Series F of the Company of our opinion
contained under the headings "Tax Considerations for Canada Life Shareholders -
Ireland Tax Considerations" in the Canada Life Financial Corporation Management
Proxy Circular, which is part of the Registration Statement.

          We further consent to all references to our firm included or
incorporated by reference in the Registration Statement.

                                               Very truly yours,

                                               /s/ Arthur Cox<Page>

                                                                    EXHIBIT 4.7

Deloitte & Touche LLP
360 Main Street, Suite 2300
Winnipeg, Manitoba R3C 3Z3
Canada

Tel: (204) 942-0051
Fax: (204) 947-9390
www.deloitte.ca

                                                                       Deloitte
                                                                       & Touche

INDEPENDENT AUDITORS' CONSENT

We consent to the incorporation by reference in this Registration Statement
of Great-West Lifeco Inc. on Form F-8 of our report dated January 29, 2003
and our report dated January 30, 2002 and incorporated by reference in the
Annual Information Form of Great-West Lifeco Inc., dated April 25, 2002.

/s/ Deloitte & Touche LLP

DELOITTE & TOUCHE LLP

Winnipeg, Canada
March 25, 2003

--------
Deloitte
Touche
Tohmatsu
--------<Page>

                                                                  Exhibit 4.8

                           [Letterhead of Ernst & Young]

CONSENT OF INDEPENDENT AUDITORS

We consent to the use in the Form F-8 Registration Statement (the
"Registration Statement") of Great-West Lifeco Inc. (the "Company") of our
report dated February 4, 2003 on the Consolidated Balance Sheets of Canada
Life Financial Corporation and the Consolidated Statements of Net Assets of
its Segregated Funds as at December 31, 2002 and 2001 and the Consolidated
Statements of Net Income, Equity, Cash Flows and Changes in Segregated Funds
for each of the years in the three-year period ended December 31, 2002. We
further consent to the incorporation by reference in the Registration
Statement of our report that is incorporated by reference in the Canada Life
Financial Corporation Management Proxy Circular and the Canada Life Financial
Corporation Renewal Annual Information Form dated March 22, 2003.

March 25, 2003                                           /s/ ERNST & YOUNG LLP
Toronto, Canada                                              Ernst & Young LLP<Page>

                                                                     EXHIBIT 4.9

                          CONSENT OF APPOINTED ACTUARY

As appointed actuary, I hereby consent to the use in this Registration Statement
on Form F-8 (the "Registration Statement") of Great-West Lifeco Inc. (the
"Company") relating to the issuance of common shares, 4.80% Non-Cumulative First
Preferred Shares, Series E and 5.90% Non-Cumulative First Preferred Shares,
Series F of the Company of my opinion contained in the Appointed Actuary's
Reports in respect of the policy liabilities of Canada Life Financial
Corporation ("Canada Life") for its Consolidated Balance Sheets as at December
31, 2002 and 2001 and their change in its Consolidated Statements of Net Income
and the Consolidated Statements for Equity for the years ended December 31,
2002, 2001 and 2000, incorporated by reference in the Canada Life Management
Proxy Circular, which is part of the Registration Statement.

I further consent to all references to my form included or incorporated by
reference in the Registration Statement.

Dated March 22, 2003

/s/ D. Allen Loney
    Senior Vice-President and Chief Actuary
    Fellow, Canadian Institute of Actuaries
    Toronto, Canada<PAGE>

                                                                    EXHIBIT 4.10

                     CONSENT OF BLAKE, CASSELS & GRAYDON LLP

TO:      Canada Life Financial Corporation
AND TO:  The Board of Directors of Canada Life Financial Corporation

         We hereby consent to the reference to our opinion contained in the
Canada Life Management Proxy Circular, dated March 22, 2003, under the heading
"Eligibility for Investment in Canada", which is also part of the Registration
Statement of Great-West Lifeco Inc. on Form F-8.

Toronto, Canada                               /s/  BLAKE, CASSELS & GRAYDON LLP
March 25, 2003<PAGE>

                                                              Exhibit 4.1

                                     CUBIST
                                 PHARMACEUTICALS

NUMBER                                                                  SHARES

CBST

COMMON STOCK                                                  SEE REVERSE SIDE
                                                            CERTAIN DEFINITIONS

                  INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

THIS CERTIFICATE IS TRANSFERABLE                             CUSIP  229678 10 7
IN CANTON, MA, JERSEY CITY, NJ
AND NEW YORK CITY, NY

THIS CERTIFIES THAT

is the owner of

    FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK $.001 PAR VALUE, OF

======================== CUBIST PHARMACEUTICALS, INC. ========================
--------------------------- CERTIFICATE OF STOCK -----------------------------

transferable only on the books of the Corporation by the holder hereof in
person or by duly authorized attorney upon surrender of this Certificate
properly endorsed. This Certificate and the shares represented hereby are
issued under and subject to the laws of the State of Delaware and to the
Certificate of Incorporation and By-laws of the Corporation, all as amended
from time to time. This Certificate is not countersigned and registered by
the Transfer Agent and Registrant.

    IN WITNESS WHEREOF, the Corporation has caused this Certificate to be
signed by the facsimile signatures of its duly authorized officers and a
facsimile of its corporate seal to be hereunto affixed.

Dated:

   /s/ ILLEGIBLE         [CORPORATE SEAL APPEARS HERE]          /s/ ILLEGIBLE
           Secretary                                                  President

Countersigned and registered:

   EquiServe Trust Company, N.A.
       Transfer Agent and Registrar

By   /s/ ILLEGIBLE
            Authorized Signature

<PAGE>

                           CUBIST PHARMACEUTICALS, INC.

    The Corporation has more than one class of stock authorized to be issued.
The Corporation will furnish without charge to each stockholder upon written
request, a copy of the full text of the preferences, qualifications and
special and relative rights of the shares of each class of stock (and any
series thereof) authorized to be issued by the Corporation.

    The following abbreviations, when used in the inscription on the face of
this Certificate, shall be construed at though they were written out in full
according to applicable laws or regulations:

TEN COM - as tenants in common          UNIF GIFT MIN ACT -----Custodian-----
TEN ENT - as tenant by the entities                       (Cust)      (Minor)
JT TEN  - as joint tenants with                    under Uniform Gifts to
          right of survivorship                    Minors Act________________
          and not as tenants in                                  (State)
          common

   Additional abbreviations may also be used though not in the above list.

For value received,                   hereby sell, assign and transfer unto
                   -------------------

Please Insert Social Security
or other identifying number
of assignee
------------------------------

------------------------------

-------------------------------------------------------------------------------
 (Please print or typewrite name and address, including zip code, of assignee)

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

-------------------------------------------------------------------------shares
of the capital stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint
                                                                      Attorney
----------------------------------------------------------------------
to transfer the said stock on the books of the within named Corporation with
full power of substitution in the premises.

Dated.
      --------------------------------

                 (Signature)
                            ---------------------------------------------------
                    NOTICE: The signature to this assignment must correspond
                            with the name as written upon the face of the
                            Certificate in every particular, without alteration
                            or enlargement or any change whatever.

     (Signature Guaranteed)
                            ---------------------------------------------------
                            All guarantees must be made by a financial
                            institution (such as a bank or broker) which is a
                            participant in the Securities Transfer Agents
                            Medallion Program ("STAMP"), the New York Stock
                            Exchange, Inc. Medallion Signature Program ("MSP")
                            or the Stock Exchanges Medallion Program ("SEMP")
                            and must not be dated. Guarantees by a notary
                            public are not accepted.

This Certificate also evidences and entitles to holder hereof to certain
rights as set forth in a Rights Agreement between Cubist Pharmaceuticals,
Inc. and EquiServe Trust Company, N.A., dated as of June 21, 1999, (as
amended to date, the "Rights Agreement"), the terms of which are hereby
incorporated herein by reference and a copy of which is on file at the
principal executive offices of Cubist Pharmaceuticals, Inc. Under certain
circumstances, as set forth in the Rights Agreement, such Rights may be
redeemed, may expire, or may be evidenced by separate certificates and will
no longer be evidenced by this certificate. Cubist Pharmaceuticals, Inc. will
mail to the registered holder of this certificate a copy of the Rights
Agreement without charge after receipt of a written request therefor. As
described in the Rights Agreement, under certain circumstances, Rights held
by Acquiring Persons (as defined in the Rights Agreement), or certain related
Persons, and any subsequent holder of such Rights, may become null and void.

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