An update from British Airways

I’m afraid your claim for compensation has been refused because British Airways didn’t operate AA6915on 13 September. If you contact American Airline they’ll be able to consider your claim. We'd also like to thank you for your patience while we got back to you about this.

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AA6915 is the BA84 operated codeshare from YVR to LHR.

EC261 places all responsibility on the operating carrier, so is this another attempt by BA to weedle out of their legal responsibilities?