How to draw James Hewitt style Illustrations (Gorillaz)?

I LOVE the style of James Hewitt, Does anyone know how he creates his Illustrations, I'm wondering how he does the lovely black outlines, is it by hand with some sort of special graphic pens or is it done in a program such as Illustrator? He uses many different weights throughout the lines, that's why I have a feeling it may be hand drawn...?

Example at ::

http://gabrielgs.files.wordpress.com/2008/05/gorillaz-murdoc-2d-noodle-russel.jpg

he's been around a while, my guess is he draws the black outline with a pen, digitises it and then adds the colour on a computer.

I have commissioned comic hero art in the past, and most artists will supply hand drawn black and white drawings, or scan them in and email them