Ok I have come back to update this thread and ask for some advice.
I booked my ticket (at the higher price on BA.com) and then submitted my price promise claim. I got a pretty quick reply telling me:
"Thank you for submitting your claim for the British Airways Price Promise. We have reviewed your claim and have found that it does not fit the necessary criteria for the following reason: The competitive fare you submitted was found on the website you provided. However we are unable to see the fare rules for the fare on the competitive website. If you have any evidence of the Fare rules you can forward it to as a Screen Shot in a document of jpeg file. We would be happy to assist you"
For a start this was total rubbish as the fare code was easy to see on the site and was exactly the same as the BA.com fare bucket. However not to be deterred I forwarded to them some screenshots clearly showing the price and fare bucket and waited, and waited some more. A month later I hadn't heard a thing so I called up the executive club. They told me that the price promise department is internet only and the only way to deal with them is to submit the form again. Of course the PP form has no field for notes for me to explain the situtation so a few minutes later i got the following response:
Thank you for submitting your claim for the British Airways Price Promise. We have reviewed your claim and have found that it does not fit the necessary criteria for the following reason:
Your claim form was not submitted by midnight (GMT) on the day of purchase.
So anyone got any ideas? The PP department appears to be impossible to directly contact and the EC were no help when I called them.