Last year I flew from LHR to ORD in first class and was the only one in First Class. Apparently three or four business class passengers complained about not being able to upgrade. Some of the flight attendants told them that I had bought the cabin out. You can imagine the strange looks on the faces of some of them when we landed and I walked out of first by myself.
This week flying from NRT to DFW in first class there were only four of us.