Even more southerly was a route that took us from SIN over Sri Lanka, up to Oman , the north over western Iran, Turkey, Bulgaria and thence to LHR - all due to the strong Jetstream over India.
For four years I used to fly frequently in between SIN/LHR and only did that route once. I reckon I did virtually every route variation in my time.
You could go to talk to the drivers in those days (which I used to do), and nearly every time the reason for the route choice was headwind related.