Mid 80's. CO was advertising new service IAH-LHR. (may have been LGW). $99 each way. I should have done that deal but was working at the time and didn't have time.

My first intl trip was LAX-London in 1994 on DL. Only paid <$400 for the ticket. Did get a bump so I got $400 cert & only arrived a few hours later. ^ Was able to use a normally useless upgrade cert (requiring full Y ) on the CVC-LGW leg since the new outbound legs booked into full Y. ^