There was what appears to be a serious medical emergency which people here seem to be ignoring. Ignoring other considerations GYD appears to be the closest airport. Going to DXB would be similar but that would require clearance from Iranian airspace. Other considerations include an A380 capable airport, advice by the ground medical advisory team,
Flight hours are strictly governed by CAA
I think it's 18hrs + i think there is possibility of extending a bit at pilots discretion.
(Its actually a lot more complicated than that)
So the typical LHR-SIN takes 14:30hrs
The diversion cost 3.5hrs
That would be 18hrs If they landed and immediately departed for SIN. However, they parked at a remote stand and would have to wait for stairs to arrive at the airport, wait for sick passenger to be transported off. Let's say GYD was super efficient and it took 2 hrs
Im saying 2 hrs based on my previous experience with a LAX-MEL with non medical diversion to SYD due to fog in MEL - in that case 2hrs ground time- landing at remote stand, stairs to arrive, bus to arrive, 5pax disembarking, refuel take off. But the aircraft is in GYD not SYD where QF has a major presence. If they then departed they would arrive in SIN at the 20hr mark. So they have already exceeded to 18hr limit and even with additional "pilot discretion additional time". The thing about pilots discretion is that it is not for anyone to demand that.
But remember the duty time clock starts ticking in LHR not at takeoff but approx 1:30hr prior.
So they would be out of hours maybe somewhere over Bay of Bengal with the 18hr limit
I'll stay overnight in Baku thanks very much. Never been there. Would be an interesting place to visit. Might even say to QF, I'm staying a few more days and I'll find my own way back. Maybe GYD-DOH-SYD or similar