As it took me ages to figure out why these two towns now seem set to enter the annals of Machin history, I thought it might help to set out, briefly, what I've learned.
Harrisons had been quite happily printing loads of our definitives and then got taken over by De La Rue in 2002. Questa had also been providing us with some interesting varieties but their Byfleet plant had also been acquired by DLR in 2002. So DLR moved stamp production to Byfleet and that gave us the first batch of 2003 varieties. Different types of print equipment and processes produce the varities we collectors love. Some of them are obvious just be looking at a stamp, others need closer attention.
Then, in 2005, DLR closed Byfleet and moved production to that permanent traffic jam of a town called Dunstable. The fact that I am a lecturer at the college there doesn't help but that's another matter! Maybe I should arrange a trip, for the students, of course(!) So that meant yet another set of equipment and new items that would be a pretty essential part of the collection.
Between 2003 and 2005 there were quite a few postal rate changes too so even items nearing the end of their useful life got new prints.
My main concern is to know which values were printed on the new equipment, what fairly obvious discerning features distinguish varieties and when they were 'issued' so that I could update my listings and also note the items I'd have to buy (before they got scarce - and expensive!)
I won't list the items I found here in full but they're on my new site in Group 7 (Byfleet ATN) and Group 8 (Dunstable RMS). A quick summary will be in the next postings.
Mike Holt has explained the detailed changes very well in his listings as has Robin at GB Machins but if you're not too concerned with what sort of paper is used or the fine detail of types of phospor then some simplification is necessary to get some sort of manageable listing. The veritable Douglas Myall's articles in the Philatelic Bulletin are excellent but I finished up very confused.