Thanks Glider.
I don't need to. I know that if we go high when heavy we slow down putting another 20 mins on a 4 hour flight. That is enough for me to stay only high 30's and get there fast. Besides, my owner cares not a jot about fuel but will argue about a tyre change!
BTW. I'm not getting much change out of £4k for a LTN visit. 3 pages of this's and that's on the bill. Then if you are a screened flight... OMG!
KH