Originally Posted by
florens
AY‘s A350 to LHR was also needed for cargo though and in fact I believe this is why it was launched in the first place. So it may come back even when the cabin space is not needed.
No, the widebodies on european routes were launched to make use of aircraft that would otherwise sit at HEL between trips to places like HKG. The timezone of Finland and shorter flying time HEL-HKG mean that there's enough time between flights to/from HKG to fit in a flight somewhere in Europe.