This week Newsnight host Emily Maitlis let her dog sleep on the seat next to her on a train to Paddington, sparking some muted outrage: somebody took a picture and posted it on social media and a couple of other people pretended to care. “For someone who is very much in the public eye, who holds politicians to account, I would have expected her to behave better,” a person known only as A Witness told the Mirror. In a statement, Maitlis said: “There was no one without a seat looking to sit down.”

Emily Maitlis. Photograph: Alex Lake/The Observer

Personally I would prefer a train carriage where every other seat was occupied by a sleeping dog, but according to Great Western Railway, dogs are allowed on trains, but never on seats, and that includes guide dogs. So what are the other rules of train seat etiquette?

Should pets be allowed at all?

Yes – as long as you remember that not everyone likes being on trains with animals, even their own pets. If you see me on a train with my dog, you can assume that something has gone badly wrong with my travel plans. I know my dog is adorable, but I am only prepared to talk about that for a limited amount of the journey. Getting an adorable pet was not my idea. Because my dog is also small and needy, it will probably insist on spending some time standing on my lap. This is not the same as a dog on a seat, and again, it will not have been my idea. I go on trains to take a break from my dog.

What about children?

I have travelled with small children, and in my experience most passengers would rather sit next to a dog than a toddler. On a crowded train, you should give up your seat for a toddler if you have for some reason come to dislike the person you are sitting next to. Older people should be offered your seat, depending on how old they seem, and not how old they are. Do not ask for ID.

Is it ever acceptable to put a bag on the seat?

No. A bag on a seat is worse than a dog on a seat. At least the dog is enjoying the ride. Even worse than bags is feet on seats. Any attempt to cushion yourself from the possibility of having to sit next to someone is both antisocial and prone to backfire – you end up sitting next to someone who hates you and they will give up their seat to the first toddler to come along.

Should you chat to your neighbours?

It is almost never acceptable to make eye contact with a stranger on a train, even if you are facing them across a table for a five-hour journey. I am very sorry my dog does not understand this.