It's actually quite frightening, as how many HEO's will have the negotiating skills necessary? Okay, it's only in a specific area which they might have expertise in, but the negotiating skills? Doubtful.
On a personal note, I left the civil service as an HEO in 1993 to join local government. I doubt that in the civil service I would have got much further, so looking at those pay grades, I can honestly say I made the right decision to move on!
Edit - having now looked at the JD's and person specs, there's lot's of right-on motivational language and clearly a lot of flexibility will be needed, I'd say the grade this is being advertised at doesn't really represent the level of responsibility and expertise they are seeking, so in short, I agree with Ash.