I too was wondering since when QF10 was operated by a 388, but I worked out the QF32 was changed to a 744 and the later departing QF10 given the beast.

Track Flight Status for (QF) Qantas Airways 10 (Select "QF 10 LHR London SIN Singapore")

It seems to have eventually departed around 2:30pm, ~16:30 later then the scheduled QF10 and ~27 hours later than the original scheduled QF32.