Paul Corfield wrote:

Just on that machines point, some machines at Euston, which are pretty
standard NR machines (can't remember the names of different machine
types) already have Oyster functionality, presumably because of LO.

Therefore, for all TOCs who use that kind of machine at least, the
work is already done without further redesign, presumably.

Yes but I don't know if those machines can set OEPs.

One thing I haven't see clearly is whether or not OEPs will be required on
London Overground (and for that matter parts of NR that currently accept
PAYG) - will the TfL branding override the NR status or does the
conscientous traveller need to carry a manual to a) do the right thing and
b) challenge any ticket inspector who disputes this?