Yes, I have had the corporate training on leaks and insider trading, too...

Trading on public information is fit and proper (Edit: Indeed, a technical term, but that does not make my statement incorrect, or does it?)

I think you may have skipped the part of leak to whom. If it is a leak to you then it is still not public and indeed insider trading. But if leaked to the public then it is different (and also how do you prevent people from trading on what they see in the media?)

But that's in general as in this case, the OBR admits they released it and, again, anyway once it's on BBC News it's free for all.