Dutchjock.
So what?
The majority of club passengers from LHR are travelling on business. I would hazard a guess that from LGW club passengers are on leisure/holiday travel.
One wants a predominantly efficient experience, the other wants a predominantly enjoyable experience. Both attributes are also applicable to each service.
At LHR 1.5 hrs versus 2 hrs equals less work time or less rest time FOR PASSENGERS. It matters. It matters when passengers sit with a dirty tray in their way whilst firing up the lap top, not because the crew are in bed or doing the mail crossword, but because the crew are busy dealing with other passengers who need sleep before startig work at the other end. More crew equals a quicker more efficient service. More crew also equals more cost, I know. There was a trial whereby a crew member was taken from traveller on the Jumbo and placed into club. I don't know the outcome.
One more point. The WW Club service takes closer to 3hrs to complete the main meal.