Originally Posted by
Mart81
Some threads here state that this is the case if under a BA flight number, so that confused me. But from a most knowledgeable user like yourself I trust it's not worthwhile upgrading them
If you upgrade it in advance via a BA service centre then you would get the extra TPs if it is under AA prime code and booked into First, yes. But the general principle of AA and US is that paid airport upgrades don't get upgraded credit on their FF schemes so they don't give that credit to anyone else either.
You may be thinking of the issue of a BA codeshare into business, which indeed does give business TPs (still an interesting 140 TPs) when for the same price, same seat on AA prime numbers gets 210 TPs.
It may be worth a call to BA to see if there is anything they can do at a reasonable rate, since a few hundred pounds there may be more cost effective than a LGW AUP.
Alternatively lose one day of your LAS time by doing the LAS-LAX or PHX-SFO shuffle, which gets 240 TPs for around £320 if booked 2 weeks in advance.