Useful stuff, thanks Sensus.
I think what was interesting about Joe's case is that the council made some clear errors (errors obvious enough that a non-professional - no offence Joe! - could spot them). It's concerning that people who are paid to know and implement the law could not only get it so wrong, but would then spend taxpayer money fighting it.
Bear in mind also that Joe did, in fact, engage a professional at the start of the process. Given how far they got him, I can understand why he took it upon himself to take the process further.
Also, Joe already had planning permission to build something. He cleverly used the same footprint for that as for the application he was appealing, so he was able to crack on knowing that whatever the outcome of the appeal, he'd still be able to build, and the appeal wouldn't be holding him up.
Perhaps not general advice to go it alone, but I suspect each case needs to be looked at on its merits.
I've also little doubt that there're planning consultants and planning consultants. In our case (and I think this is pretty common), there's a planning consultancy directly across the road from the planning department, and it's staffed mostly with ex-planners, including the ex-head of the department. I personally know two people who've employed them with huge success. Poachers turned gamekeepers (or is it the other way around? )