Recently the LHR /DEN route restarted and since the restart they have exclusively used one of the 14 refurbished 77M, 777-200ER. With the exception of the G-RAES, they are all of the G-VII series. These refurbished 777's all have a 4 class config with 8 F seats. However none of the flights to/from Denver offer F for sale. (or Avios). Why would that be? Staffing for F? Just leave the F cabin empty or offer to Gold?