I’m not really an advocate of capital punishment, but I’m prepared to make an exception for people on the Tube with those suitcases you pull behind you. We can no longer tolerate the brandishing of solid objects immediately below the average adult’s line of sight. I’m especially thinking of those people who take one step off the train, or pass through the ticket barrier, then stop dead to pull out the case handle. (We aren’t even going to begin to discuss people who stand on the left.) You have all been warned.