Probably one for Jumbodriver and co.

Having a read of the GUess when premium cabin fares will fall thread I was having a think about the marginal costings of flying and was wondering just how much extra fuel a BA pilot would add to the tank on hearing that rather than a seat be empty my average male behind (plus the usual attachments! ) along with my average amount of baggage will be aboard?

Let's say I'm flying LHR-SIN.

And I'll press for bonus Mucci points to be awarded for saying how much said fuel will cost.