We’ve not seen one of these before anywhere else on the network until we walked past this one at King’s Cross the other day – targeted presumably at people leaving London on the Eurostar.
Rather then leave unspent money on an Oyster card (and apparently there’s quite a lot of it sloshing around the system) you can drop your unwanted Oyster off here and any money on it will be taken back (including the £3 deposit, we wondered?) and given to the Railway Children charity.
We haven’t seen them anywhere else, but I wonder if there are also similar boxes down at Heathrow airport too …