I am sure there were many automatic caning offences but the most common one was being sent out of the room and stood facing the wall. If that was early in the lesson, you would be very anxious and hope that a patrolling senior master would not come along before the next lesson. If he did, then you would be soon touching your toes in another room for 2 or 3 strokes of the cane and then escorted back to your lesson if time allowed.
I forgot the multiple detentions one. I think it was three detentions in the same term at our school that warranted a caning.
Sorepants – At mine missing a detention earned a caning and you still had to do the detention at the next opportunity.