This stamp is a bit of a curio. A Penny Patrician printed by letterpress, a centuries old technique. According to the Wincanton news release in April 2005 – Recognisable because the paper is thinner (80 gsm) than the normal Penny’s , and the printing process is one we have never used before.  The other difference is in the letters in the corner cartouches of the stamps, which bear the letters H-V & A-M 
The stamps have been produced on a very old Heidelberg letterpress.  The letters or plate are clamped into a frame, a printing form supplies the ink before this is covered with the sheet and pressed on to produce a ready-printed sheet which can be reproduced indefinitely.
It is an old and tried process, which gives the stamps a unique, slightly antique look.  The plates are of zinc, and therefore do wear out quickly, so we are only doing the one print run.  Of the 350 sheets (of 56 stamps) produced, 250 were made available to subscribers of the Stanley Howler Stamp Journal for 30.00 and came in a special acid free folder and with a individual numbered letter of authenticity.  The remainder were perforated at Wincanton and split up to be released in LBEs. Unlike all the other Penny Patricians except the Enschede this stamp has a different paper and gum. It appears a bit yellower from the back and lacks the roughness of the gum.
This process results in a very monochrome stamp, with only black ink being used. This result is certainly rather in keeping with Ankh-Morpork technology, but out of step with all the other stamps!. There is a sport of this stamp. One stamp per sheet has the V in the top left cartouche sloping to the right.

    
The sheet and insert - click for a larger image

The more cynical or more knowledgeable may say that this was an attempt to obtain a reprint of the stamps for a cheaper price than Enschede or the artisans of East Anglia even, but the quality left much do be desired, and the sheet offer may have been to recoup losses.  Thus there were 5,500 common single copies of this stamp, and 100 of the sport. Each sheet is individually numbered.  These were dispatched with a large AM Duty paid stamp used on the packaging.

The actual number of single stamps available to collectors is actually lower than that quoted above. The one penny stamps used on the Dragon Sanctuary covers were exclusively the Penny Civics, and very occasionally one of those is a Civic Sport. Four of the covers used eight stamps between them, so that reduces the single copies down to 4,700 (or less).