TfL has been saying for a few years that Oyster will eventually be withdrawn, but not until contactless payments can offer railcard discounts.

“There is a man who must be chastised,” she says softly, lightly. “Chastised in a physical way. It should not be difficult. Not for you.”

Below is the deep abyss of the Lauterbrunnen valley, and at its head a stately semi-circle of mountains, with the pyramidal Lauterbrunnen Breithorn as the centre-piece.

What happened to the man who was to be her guide is unclear, but the pony-tailed girl met up with a group and pressed on, vigorously swinging her arms to keep up as they trekked north through the Rio Grande Valley on Sunday under a half-moon.