Sphere 1977 paperback (copyright 1974 in U.S.A.) Cover by ???, 189 pages, 75 pence price on back cover. Condition is VG+ to near-Fine: tight and square with flat spine; age tanning is mild and uniform; very light overall wear. Previous owner's stamp and price on first page; no other marks, stamps, or writing.

A nice British paperback of The Secret Galactics, a novel by A. E. Van Vogt. In my opinion, this is the nicest looking edition it has had. This orginally came out in 1974 in a trade paperback from Reward Books - who used a poorly drawn cover that would scare away most readers of serious SF. British publishers kept this title in hardcover and paperback, but the American mass-market paperback from DAW Books changed the title to Earth Factor X. While this cover is in the Chris Foss style (he was the most sought-after British SF cover artist of the Seventies) - I'm sure it was done by someone else, who was told to "make it look like Foss." (Perhaps Eddie Jones?)

Since I haven't read this, here's the back-cover copy:
EARTH FACTOR X
Reality twisted... slightly. Earth shivered. For a split second the Solar System wasn't. And then was again. Less than a billionth of a second - but a time shift had nonetheless happened.
As the shadow ship started to emerge from the time jump, men and aliens were locked in a secret, undeclared war for control of the Earth. Genetically altered, the aliens looked exactly like humans. And they were in positions of power everywhere. Opposing them were 2 humans and one isolated brain in a mechanical body. But between them they held the one secret that the aliens had never learned about the people of Earth...