In response to a query.

I used a Pentel propelling-pencil with 0.5mm H leads. Inked with a fine Gilliot knib in a`schoolboy' pen handle. Depending on pressure used it was capable of a hair fine or an eighth-inch thick line.
Higgins waterproof black ink for it's easy flow and that a blob of dried ink did not build up on the knib.
Initially onto hard smooth CS10 board later on a coarser, little more absorbent and much cheaper board. Save for DC and Marvel who supplied card.
Colouring with Ecoline water-colour inks for their intensity and transparency.

For the curious there is more about my working method in the 2000AD interview reachable at  2000 AD review.