[The race controller]

A good idea, we have some down at the track.
A quick look around the track and I'll see straight away who is marshalling and who should be penalised for not doing so.
To make it even more strict we could have you stay at your marshalling point until you're relieved. It's bad enough when you wander off before the race has finished. (I blame the PA for that. It not being clear due to the echo of the room)