It's the herd instinct of the commuter: you need
one of these.

Except with written permission from an Operator or an authorised person, no person shall bring with him or allow to remain on the railway any item which, in the opinion of an authorised person, may threaten, annoy, soil or damage any person or any property.
Hmm, do
FGW▸ give out written permission to carry cattle prods?
