Mike, your post about validators at Farringdon reminded me of something I’ve been meaning to mention.
Using Oyster PAYG, I change at Rayners Lane quite often on the way from the northwest Met to Heathrow or similar and of course always touch a validator on platform 2 (south/eastbound) there to show that I’m avoiding zone 1. And I get the cheaper fare.
When I first started doing this some years ago, the validators were pink as you’d expect. Sometime “recently” the validators changed to yellow. I say “recently” because as I didn’t travel for a while during you-know-what the change could have made in 2020 for all I know.
The validators still work as a pink validator should, showing “Intermediate validation” on the Oyster app and applying the cheaper fare. I last went that way as recently as 18 April. They’re just yellow not pink.
Both this site and the TfL single fare finder still recommend touching the pink reader at Rayners Lane.
Unlike Farringdon, Rayners Lane is a simple station with a single gateline at the single entrance so the platform validators are only for people avoiding zone 1. Confusing…