I don't win the internet for this one,
LHR-HND-LHR in WTP (unrefurb 772 both ways) for 6 days. On paper it was 6 but as the HND-LHR is early morning it was more like 5+.
Booked on a whim in a cafe one lunchtime as the fares were good and I had always wanted to go to Tokyo.