Just bear in mind @
Jimmie Jones, I think i'm right in saying that the general consensus is that UC (aka business class) is much more sought after (and as a result rather more expensive) on a daytime flight than it is a night flight so unless the flight is really empty (which it never is on flights to LAX) I'd be astonished if you found a cheap upgrade (and for the purpose of this conversation i'm calling £700 cheap!!!!).