WHEN THEY COME FROM SPACE by MARK CLIFTON. Doubleday, 1962. Hardcover in jacket. BOOK CLUB EDITION.

This was serialized in AMAZING as "Pawn of the Black Fleet." Due to mistaken identity and ironclad bureaucracy, our hero is forced to deal with an alien invasion of Earth, even though he has no qualifications for the job.

Clifton was a noted SF writer of the '50s and early '60s. He co-authored the Hugo winner of 1955, THEY'D RATHER BE RIGHT.

Always happy to combine shipping on multiple wins. 

Note that the foreign postage prices are a guess. If they prove too high, I will refund the difference.