I got very lucky over the Christmas holidays this year. I was a PLT flying LHR-ORD-LHR and got op-ups to business both ways! The first flight was on 24 Dec and the return on 2 Jan. I think that both of those dates probably had lots of families traveling but not as many business travelers, so I have no doubt that coach was oversold with plenty of seats still available in business.

Regardless, I felt quite fortunate--my last op-up was while going to visit a college from Denver-Boston, over 8 years ago. I don't even remember the airline but I had no status.