Originally Posted by Jetstreamer

Be aware that if you book a round trip LHR-HKG-LHR, you will pay YQ on the HKG-LHR sector. Only if the trip originates in HKG can you avoid the YQ. Not sure how they can get away with this but they do.

That is why the advice is always to book two separate tickets when redeeming to HKG and back. However with the voucher you can only use it on one ticket so you have a choice whether to use the voucher both ways and pay more YQ or use it one way only and save YQ but spend more Avios to fly PE. Tough one!