I recently booked a MLE reward flight... LHR-SIN-MLE, and back MLE-SIN-BKK-LHR.

Cost... same as LHR-MLE direct (if there had been one)... as this was the most direct routing available on *A.

The good thing is... you can stopover each way in SIN... (as it is outstide Europe, and is therefore not limited to the intra-EU stopover maximum of 24 hours)

Also, have previously travelled LHR-NRT-SYD... but as there is no direct NRT-SYD on *A, was able to route via SIN, which is backtracking, but permitted as it is the most direct routing available.