This morning I travelled into Clapham on South Western Railway from Aldershot using a weekly season ticket, then I changed to use the over ground out of platform 2. First time I did this to avoid using the tube due to strikes today. I did not pass through a barrier so just got on the over ground and got off at Whitechapel which is a zone 2.
By failing to touch in, you travelled without a valid ticket and therefore could have been issued with a Penalty Fare, or prosecuted. That said, with contactless, due to the way the system works there is no way of inspectors knowing whether you are actually touched in at the time.
But a maximum fare would be charged once the inspectors' "inspection records" are reconciled in the system at the end of the day. I understand there is also a "three strikes" policy, after which your card would be blocked from any further use on TfL.
What will the penalty or fare be?
A maximum fare of up to £8.90.
You can contact TfL customer services and explain the mistake you made. They may refund you the difference, but it's at their discretion.
Should it have been £1.70 for that journey normally?
£1.80 as of today's fare increase, if touching in between 06:30-09:30 (or 16:00-19:00).
Should I have found one of these pink card readers and tapped IN at Clapham on platform 2? Then out on the normal Whitechapel exit?
Pink readers
can be used to touch in, though that is not what they are designed for and there is a chance that TfL may remove this functionality in the future. But either way you should have touched in, in some way. Simply boarding without touching in means you are travelling without a ticket.
When I go home tonight and I tap in contactless at Whitechapel, what do I do when I get to Clapham to terminate and tap out my contactless journey on the over ground? Do I have to go find the Yellow one on platform 17 or will the pink one be ok again? I obviously want to stat station side to change trains to an SWR one to get home on my normal season ticket.
You can only use pink readers to indicate the route you took, or to touch in. You cannot use them to touch out - otherwise people's journeys would be ended when they were just meaning to indicate their route!
You will either need to touch out at a yellow reader, or at the ticket barriers. There is no requirement to actually pass through the gate, you could just touch out and immediately return to the platforms - though that could arouse suspicion from gateline staff.