Thanks UKtravelbear

I had imagined, perhaps incorrectly that such ATM deposit machines would be inside some sort of vestibule or airlock, so even when the branch is closed, the machines would be accessible.

It's just occurred to me that Santander on Oxford Street near M&S Pantheon is huge and the banking hall is on the first floor, but I cannot recall what the ATM set up is and whether the ground floor is accessible when the branch is closed