Originally Posted by
happyhat
It starts with an 001. Leg #1 is codeshare w/ American (BA metal). Leg #2 is pure BA. I was told my AA that SWU's only work on flights marketed and operated by American, so it would seem like the SWU is a non-starter.
If it is BA marketed and operated then you can use AA miles (not SWU) in certain circumstances (basically not any kind of discount fare, and maybe booking restrictions). But if you are booked in Economy then an upgrade will only get you to Premium Economy and it will cost you in extra surcharges.
Check the BA Forum's AUP thread for Airport Upgrades - you should be able to pay for an upgrade at SAN and again at LHR that will get you into Club and will learn you Club LPs (at J fare) or Club Tier points and AVIOS. These AUPs will probably cost around $700-800 SAN-LHR and £350-450 LHR-RUH - but the thread on AUPs will show you real prices that people have paid.