Well their website states:
"We kindly request that you do not bring the following items within your luggage:
* Any weapons
* Drugs or solvents (other than medicines)
* Live or dead animals
* Fish or insects
* Battery powered wheelchairs/disabled scooters, unless they are pre-booked
* Prams
* Non folding pushchairs
* Non folding bicycles
Any other items considered unsuitable for carriage by reason of their weight, size, shape or character."
It's rather vague, and I'm sure a telephone money would probably just read that list straight back to me. Also, it's not just wether it's against the train companies rules, but also the actual law in general. I got randomly stopped and searched last time I was at an inter-city train station and would rather not be wandering around with gas in my bag if I don't know about its legality. I've sent them an email anyway.