Apparently ZNA came in 1.5T underweight. That supposedly has worked very positively in QF’s favour.
If true, it
will be a very positive thing. I don't know if PER/LHR will be a full tanks operation but if the OEW (OWE) is less than expected, it would normally mean either a greater fuel uplift, more payload or a combination of both. This would also apply to any sector at MTOW.