Where do the sayings on the wagon and off the wagon come from?

Answer 1

Back in the olden days in London when they had public hangings they would drive the inmates from tower hill where they were kept to the public town square to be hung. On the way they would stop at a local pub and let the Inmates have one last drink. The guard in the back could have a beer but the driver could not so when they asked what he wanted the driver would say" I am on the wagon" this is also where the saying One for the road comes from because the inmates would always ask to have another drink to take with them or "One for the road"