Essay writing skills (Case study: Man In Iron Mask)

Exactly what qualifications are necessary before writing an essay the standard of Staff report : Who was the “Man In The Iron Mask”?

In my opinion it is an excellent piece (informative, factual, methodical style), and bar some reservations (a little too much first person - I guess as can be expected really) it deserves accolades.

My point is, how is it that the writer is able to write the essay in such a style? What qualifications (not job-wise - but it would be interesting to note exactly what skills he/she has picked up along the way) are necessary to develop this “technique” of essay-writing into a skill?

It appears as though nothing has been missed out and there is ample probabilistic determination (i.e. what events are likely/what events are unlikely) with critical assessment throughout.

I can’t imagine that there wasn’t absolutely cartloads of information to sift through. It’s such a long legend. So how long would it have taken him/her to review all the data and draw conclusions?

There are books out there that teach better essay writing skills but none really give a hands-on approach (it’s usually so general). If anyone has any recommended books by the way, please point me to them as I am desperately in need of this skill.
So how exactly has he/she moved from point A to Z when completing the essay?
[Note to mods: I put this in C on S Reports b/c it is this particular piece I am interested in].

The author of that piece is very pleased and flattered at the compliment. An answer would be far more autobiographical than Xavier would like, but basically the “training” came from:
(1) - 25 years of writing business reports, which requires condensing massive information into easily digested, somewhat shorter (although you wouldn’t know it from the lengthof the Iron Mask report) reports
(2) - Faithful reading of Cecil’s columns, and years of working with Ed Zotti (Cecil’s editor)