I have just got off a BA flight London to Dublin, where the crew did not the check the boarding passes at the door of the plane. Always of questionable use when the gate agent has checked them 2 minutes before, they often cause problems and confusion for passengers unfamiliar with this quirk.
Apparently it’s gone now from Domestic and European flights, but lives on when travelling on Intercontinental and Long Haul flights.
So put those boarding passes away if you’re going to Europe with BA.
The ‘checking of boarding passes on the plane’ was introduced after one of the terrorist threats / attacks. Done to ensure everyone had the right to be on the plane – I assume it’ll also be dropped at all UK & European airports, even those like LCY where anyone can roam onto the plane.