Originally Posted by Ldnn1

p.s. I originally read your OP as indicating you had found O class available on BA.com for the 23rd, but at a different price to that found on EF. In fact you weren't finding O class on BA.com at all but a higher fare class - in this case Q (based on current availability). You would have been able to see that by clicking on the flight details box at the flight selection stage, where it tells you the class being offered.