The basic premise of the book is an interesting one and is similar to a theory put forward by Carl Sagan in his book, "The Dragons of Eden." In "Dragons . . ", Sagan argues that the innate fear that humans have of reptiles is a genetic remnant of the struggle for dominance that took place between reptiles and mammals millions of years ago. Aldiss explains the human fear of vampires as another relic of the development of the human species, describing vampires as a separate species, evolved from carrion eaters. While that is an interesting premise, the story line meanders too much to be consistent.
He introduces a train used by the vampires to move through time, and the humans capture it and use it to their advantage, ultimately via time loops that are not well explained. The capture of the train is simply too easy, a device this critical would be very well guarded by the vampires and they would have mounted an all-out offensive to recapture it. The ultimate bomb used to destroy the vampires exceeds the bounds of the number of "new devices" that are allowed in a science fiction tale.
I did enjoy the inclusion of Bram Stoker, the author of the original Count Dracula vampire story. The description of this man of Victorian times is without question the best part of the book.
This was not a book that kept my attention. The story meanders and the actions of the vampires in allowing the capture and possession of the time train while they are capable of sucking blood from the neck of the thief was just too much. I finished it, but this is one tale that did not excite me.