This is something of a postscript to the piece below.
There has been some discussion on trigan.com's message boards about how much editing has been done on the Trigan Empire: The Collection volumes which I believe was sparked by the entry for 'Trigan Empire' on Wikipedia. Recently it was noted that "The Trigan Empire Collection reprints are edited versions of the originals," which caused some consternation amongst fans of the strip.
The premise behind the Trigan Empire: The Collection series is to give fans the best versions of the strip that we can. That means we've used original artwork wherever possible, even where it was only a half-page -- we've not tinkered or tampered with it as they did with the Hamlyn The Trigan Empire volume, or abridged the strips as they did in the Hawk Tales of the Trigan Empire volume.
However, the lettering on the original boards was often missing or had been stripped off and replaced with Dutch text for the reprints that appeared in Eppo so we knew from the start that we would have to redo all the lettering. It also gave us the opportunity to fix any minor problems in the text -- but I must emphasise that any changes to the text have been minor, almost always for consistency and very occasionally a change of emphasis (a phrase in bold, for instance) or grammar (mostly removing ellipses ("...") where the original typesetter had used them to balance a balloon). In some of the early stories we have removed unnecessary recap captions. Otherwise the text is 100% taken from the original printed copies of the strip.
A second area of confusion is over story titles. The original strip never included titles for the individual stories -- it was always simply called 'The Rise and Fall of the Trigan Empire' or 'The Trigan Empire' until 1974 when it became 'More Adventures of the Trigan Empire'. When I first started indexing the strips that had appeared in comics back in the 1980s I was swapping information with a fellow collector called Gary Armitage and we worked out a reasonably neat way of presenting the information that I went on to use in various indexes published by Bryon Whitworth. This included breaking down long-running titles into individual stories and identifying them with a title -- mostly just the name of the main villain as it made keeping track of and identifying reprints a lot easier.
The editors at Hamlyn created titles for some early stories with their The Trigan Empire reprint in 1978 and Hawk Books did the same for their volume Tales of the Trigan Empire in 1991. The Dutch reprints of the Trigan Empire strip were given titles when they were reprinted in albums. Fan sites such as trigan.com have also invented titles so they can distinguish between stories when they discuss them on their message board.
So, upwards of five sets of titles have been invented for some strips. When we came to do Trigan Empire: The Collection we used a mixture from various sources which seemed to best describe the stories. I don't think of these as 'official' titles but we try to use them consistently when referring to stories in introductions to the various Collection volumes. Perhaps the question of titles is something we can address in the final (12th) volume when that appears so that we can cross-reference all the titles given to stories to make sure everyone knows which strip is being discussed.