Just by way of update on my OP.
Slightly different situation as I mentioned in the thread my purchase history showed some short ticketing, I decided that I didn't want to chance addressing it myself and took the decision to fess up and instruct a lawyer. I'm awaiting an outcome but I expect to have to pay for all the short tickets plus some kind of fine/compensation to CR plus legal fees. Hopeful to be able to settle out of court and wipe the slate clean. Costly affair but I got what I deserved for poor decision making.
I would advise anyone to think twice about boarding a train without the right ticket. You might get away with it but if you don't it really isn't worth it and they are definitely ramping up checks.
I appreciate the advice from people on this forum on the issue.