Neil Williams wrote:

Unless ticket machines are replaced with Oyster issuers, and even if
they are in some cases, people will still, quite reasonably, want
singles. This is not an excuse to rip them off.

No, but if people do gravitate across to Oyster in sufficient numbers,
it will quickly become disproportionately expensive to maintain the
infrastructure to handle these tickets, won't it.

--
http://gallery120232.fotopic.net/p11857686.html
(Both gone: Hastings DEMU 1035 under Charing Cross's glass roof, 1980)