unigamer

wayne: Thanks for the advice, will look at this more carefully. I appreciate your help and efforts in getting this hobby properly recognised.

kenneth: I am aware you can buy smoke pellets and a whole load of other stuff off the shelf, for us (and I'm sure most other people here) that's not really the point. The enjoyment is in doing it yourself. If we're unable to make our own then we simply won't do it.  Thanks for the link though.

Thanks for the answers everyone, I can see it's as clear as mud. I know it'll be crude compared to what some of you guys get up to but we do enjoy making them and we do it safely, would be nice to know for sure how to do it legally!

It's very frustrating, all my hobbies seem to be a battle with legislation: bushcraft (the knives can be viewed as offensive weapons), quadrotor/RC flying (the limits on radio power and frequencies used along with the tabloid histeria of drones) and unicycling (a unicycle falls between legal definitions for what can be used on a road and on a pavement)!