[Form of Opinion of the Senior Legal Counsel of BP Canada Energy Company]


                                                                     Exhibit 5.3

                    [LETTERHEAD OF BP CANADA ENERGY COMPANY]


BP Canada Finance Company
240 - 4th Avenue, S.W.
Calgary, Alberta
T2P 4H4

Ladies and Gentlemen:


In connection with the registration under the Securities Act of 1933, as amended
(the "Act"), pursuant to a shelf registration statement on Form F-3 (File No.
333-110203)(the "Registration Statement") of US$9,147,000,000 guaranteed debt
securities (the "Securities") of BP Canada Finance Company, a Nova Scotia
company (the "Company"), I have, as counsel to the Company, examined such
corporate records, certificates and other documents and considered such
questions of law as I have considered necessary or appropriate for the purposes
of this opinion. All capitalized words herein not otherwise defined shall have
the same meanings as set out in the Indenture among the Company, the Guarantor
and the Trustee filed as an exhibit to the Registration Statement (the
"Indenture").


Based on such examination, I am of the opinion that:

1.      The Company has been duly incorporated and is validly existing under the
        laws of Nova Scotia.

2.      When:

        (a)     the Registration Statement has become effective under the Act;

        (b)     the terms of the Securities and of their issue and sale have
                been duly established in conformity with such Indenture so as
                not to violate any applicable law or breach of any agreement
                binding upon the Company;

        (c)     the terms of the Guarantee have been duly established in
                conformity with such Indenture;

        (d)     the Securities have been duly executed and authenticated in
                accordance with such Indenture;

        (e)     the Guarantees have been endorsed on the Securities and executed
                as contemplated in such Indenture; and




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        (f)     the Securities have been issued and sold as contemplated in the
                Registration Statement,

then the Securities will constitute valid and legally binding obligations of the
Company in accordance with, and subject to, the terms thereof and of the
Indenture.

My opinions expressed above are subject to the following:

        (a)     the effects of any applicable bankruptcy, winding-up,
                liquidation, insolvency, fraudulent preference, re-organization,
                moratorium or any other laws affecting the enforcement of
                creditors' rights and remedies generally, including, without
                limitation, the applicable provisions of the Bankruptcy and
                Insolvency Act (Canada), Winding-Up and Restructuring Act
                (Canada) and the Companies' Creditors Arrangement Act (Canada);

        (b)     general principles of equity which may apply to any proceeding
                including, without limitation, the powers of the court to stay
                proceedings before them, to stay the execution of judgments and
                to relieve from the consequences of default and the discretion
                of a court to review or limit the recovery of legal fees or
                other expenses;

        (c)     equitable remedies, such as specific performance and injunctive
                relief, may only be available in the discretion of the court and
                accordingly may not be available as a remedy in any particular
                circumstance;

        (d)     claims becoming barred under laws regarding limitation of
                actions;

        (e)     the Judgment Interest Act (Alberta) limits interest on a
                judgment debt;

        (f)     the Currency Act (Canada) precludes a court in Canada from
                giving a judgment in any currency other than Canadian currency;

        (g)     I express no opinion on any provision governing the Securities
                which may provide or have the effect of providing for a higher
                rate of interest after than before default or for the payment of
                rates and/or fees which may exceed the "criminal interest rate"
                provisions of the Criminal Code (Canada);

        (h)     enforceability of rights of indemnity may be limited to the
                extent that any such indemnity is found by a court to indemnify
                a party against the consequences of an unlawful act or is found
                to constitute a penalty or be against public policy; and

        (i)     the application by a Canadian court of the laws of New York in
                respect of the Securities, as to which I express no opinion.

In rendering this opinion I have, with your approval, relied as to all matters
governed by the laws of the United States or the State of New York upon the
opinion of D.B. Pinkert, Assistant General Counsel to BP America Inc., delivered
to the Company, among others, on this date. Except for reliance on the opinion
noted above, this opinion is limited to the laws of the provinces of Nova Scotia
and Alberta and the laws of Canada applicable therein. I wish to point




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out that I am a member of the Law Society of Alberta and do not hold myself out
as an expert in the laws of other provinces.

I hereby consent to the filing of this opinion as an exhibit to the Registration
Statement. In giving such consent, I do not admit that I am within the category
of person whose consent is required under Section 7 of the Act.

Yours truly,

BP CANADA ENERGY COMPANY


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Francine Swanson, Q.C.
Senior Legal Counsel