Both my worst and my best GF crews have been LHR-based and on the overnight IAD-LHR flight. The small touch I remember most from the good flight (why dwell on the bad one, other than this FT) is that the GF FA never refilled my water glass. She simply brought me a new, clean glass each time with a lemon slice with a new napkin and just swapped out the used glass and napkin. No small detail missed!