On 11 Sep, 19:14, "John Salmon" wrote:
I thought 'out of credit' Oyster cards wouldn't let you *in* to the system,
rather than out.

It seems that my partner managed to "break in" on our return journey
by tailgating a group having problems with ordinary tickets and who
were being allowed through by a member of staff. Still waiting for the
online Journey History to be updated for both our cards so I can work
out what happened.