Same message here for the lounge in Seattle:

Dear Peter M,

Thanks for letting us know what happened at Seattle airport when you were flying to Miami last Friday. I'm sorry for the delay in responding to you. I realise how disappointed you must have been when our staff member wouldn’t let you enter our lounge. As a valuable Gold Guest List member, I certainly understand why you’re feeling let down.

I know having access to our lounges is an important part of your Executive Club membership. The British Airways lounge in Seattle's South Satellite terminal is only available for customers travelling on British Airways operated flights. Due to space constraints in our lounge, and customer feedback, we are unable to accept customers not travelling on British Airways operated flights.

As a valued Gold Guest List member, you can use our lounge when travelling on a flight operated by a oneworld partner, provided your flight operates from the same terminal as British Airways. Unfortunately in Seattle, American Airlines operate from Concourse A of the main terminal, which prohibits entry to the British Airways lounge in the South Satellite terminal.

If you would like more information about our lounges, simply click on the following link: http://www.britishairways.com/en-gb/executive-club/tiers-and-benefits/lounge-access/

Thanks again for contacting us about this and for giving us the opportunity to explain our position. We appreciate your support as a member of our Gold Guest List. I hope we can welcome you on board again soon. Please feel free to contact me directly, using the blue link below if I can help you with anything else.

Best regards

(Name removed)
Gold Guest List Customer Relations