Bodley Head , 1995
"I was reading The Great White Shark Fact File when the doorbell rang..."
Agent Z and the Penguin from Mars was dramatised by the BBC in 1996 (starring Duncan Barton, Andrew McKay, Reggie Yates, and scripted by Jeremy Front). The two lasting things I got from the experience were a) a plastic meteorite and b) a friendship with the producer, Marilyn Fox, which kick-started my script-writing career.
You can see Random House's hipper and more twenty first century cover here.