Originally Posted by
Yonasl
HEL-LHR. The route is served by an A350 with premium economy seats
Just be aware that the HEL-LHR route is normally served by Finnair A350s which have the original business class configuration and no premium economy.
See
Finnair Airbus A350 - aeroLOPA | Detailed aircraft seat plans
Very occasionally - 3 Feb is an example - an A350 with the new AirLounge business class configuration is substituted, and this does have premium economy. If your flight is showing premium economy then you've struck lucky, but don't assume it will stick.