For info: Brymon Airways(Dash8 & EMB145) have banned flight deck visits. The document does'nt say but by just a little lateral thinking this bans commercial jumpseaters)always at the Captains discretion) as well! As a result of this understandable direction I had to refuse in flight access to a 5 year old girl and her 3 year old brother. Still we got them up for a look after landing. I am very glad to say that their parents were very understanding & supportive when I explained why I had refused.