I think it's safe to assume that E-Train... and Last Train... are one and the same thing, with them both having been assigned identical catalogue numbers and release dates. I do wonder what the inspiration behind the name "E-Train To Trancentral" was (I agree that it could be to do with late '80s UK rave/drug culture), although I've always assumed "Last Train To Trancentral" was so called after The Monkees "Last Train To Clarksville" (the Monkees featured briefly on "1987")

the "last train to clarksville" reference makes sense, and would certainly suit their style the rave/drug connotation of "E-train" also sounds right on plus the double meaning, that taking an actual "E-train" on urban metros is a common thing (NYC, for example, has an E-train)

I agree that Last Train (or whatever) and Go To Sleep are odd, given that they seem to share much of the same stuff but were both scheduled for release. Of course, the final Go To Sleep could, just as the LP version of Last Train To Trancentral was, be very different from the version we're used to. Again, even though Go To Sleep was scheduled (did they run off sleeves for it?) it seems it wasn't ever going to be part of the Pure Trance series. Someone on the list has already pointed out that PT5 was possibly the last one as it's the only one that doesn't have "Welcome To The Trance" under "Other Data" on the vinyl label; instead having "Go To Sleep".

Finally, where does "Lover's Side" fit into all this? It seems to be intimately linked with Last Train To Trancentral, but I can't for the life of me figure out why...

So, if one were to attempt a family-tree-or-timeline-style of looking at this: {"wichita lineman"} / {"last train" (remix 1)} = {"last train" (pure trance)} or {"E-Train"} (unlreleased) and/or {"last train" (1988 original trance)} = {"E-Train"} then {"E-Train"} concept evolved into {"iron horse"} and {"lover's side"} concept evolved into {"last train" (white room)} and {"last train" (lost continent)} some obvious speculation here, but approx. correct?