747s at LTN?
On Sunday afternoon I was on the canal near Leighton Buzzard when a 747 flew over heading roughly north. At a guess, this was at about 5000 feet, although I don't have much experience to judge this by.
There's always a lot of LTN traffic around this area, but I'm wondering whether the one I saw was likely to have come from there or was just a low-flying LHR departure.