Gran Tierra Energy (GTE) S-3/A Shelf registration (amended)

Exhibit 23.7

Huddleston & Co., Inc.

Petroleum and Geological Engineers

1 Houston Center

1221 McKinney, Suite 3700

Houston, Texas 77010

Phone (713) 209-1100 · Fax (713) 752-0828

October 8, 2008

Mr. Martin H. Eden

Chief Financial Officer

Gran Tierra Energy Inc. (Gran Tierra)

300, 611-10^th Ave SW

Calgary, Alberta T2R 0B2

Re: Gran Tierra Registration Statement

Form S-3

Filed with the U.S. Securities Exchange Commission

Dear Mr. Eden:

As the former independent reserve engineers for Argosy Energy International (“Argosy”), Huddleston & Co., Inc. (“Huddleston”) hereby confirms that it has granted and not withdrawn its consent to the reference to Huddleston’s review of Argosy’s reserves in the form and context incorporated by reference by Gran Tierra in this Form S-3 registration statement, as amended, filed with the U.S. Security and Exchange Commission.

Respectfully submitted,

HUDDLESTON & CO, INC.

/s/ Peter D. Huddleston

Peter D. Huddleston, P.E.

President