M, no question. The jobs given out might not be tasteful, pleasant or easy, but you know that they are important. You will be given whatever equipment you need, if it is available. Favours from others will be called in if that will help you. After an initial discussion, you will be left to get on with them in your own way without any back seat driving. You will be protected from interference or criticism from outsiders (although you'd better go to Nomex for some underwear if M thinks you've messed up). Breaking laws, rules and necks will all be forgiven if you get the job done.

Of course, I'm talking about the original M from the books, not the weirdos who appear in the films, some of which I haven't seen.

Regards,

John Davies

Update 2014-08-09: http://www.telegraph.co.uk/finance/think-tank/11023448/Three-ingredients-that-can-make-any-job-the-best.html makes some interesting points about what it takes for a job to be "the best".