A British evacuee's sensitive memoir; Thanks to Hitler, a 7-year-old discovers America; America, Lost and Found, by Anthony Bailey. New York: Random House. $9.95.

Life on Britain's "home front" during World War II was more than danger and bombings, tragedies and great courage. Quite a lot of it was stumbling home in the blackout, washing clothes and the kitchen floor in the same soapy water, longing for a banana and a pencil that wasn't simply unvarnished wood. It was being delighted with an onion for Christmas.It was powdered egg.

It's easy to forget how marvelous it is not to have Spam for dinner. It is even easy to forget those terrible farewells. Servicemen and women were forever parting, children being packed off to stay with Aunty ("until the bombing's over"). No wonder so many of our songs were about saying "goodbye" ("We'll meet again some sunny day.").

Anthony Bailey reminds us of some of the most poignant neglected farewells of all --when parents sent their children off across the enemy-infested Atlantic to safety in the United States. For all they knew, they were saying goodbye forever. If anyone else has written about the evacuation of the 16,000 British children, I doubt if they have conveyed more sensitively what it was like to be one of them. But this isn't a solemn book. It's a skillful account of a small boy growing up in a wealthy Midwest household, seeing it and the town with fresh , unbiased eyes.

And though it is seen through young Tony's eyes, Mr. Bailey has brought to his account all his mature skill as a writer. The generous host family emerge as complete, delightful individuals.

As Mr. Bailey says of another piece of his writing, it's a recollection "of a time and place not that long before but already . . . lost."

So young Tony, aged seven, learned to hold his fork in the right hand, salute the flag, hide his spinach. He discovered the American way of business on a paper route. And on Halloween he collected a silver dollar from the pioneer aviator Orville Wright.

After four years and another farewell, Tony Bailey arrived back in England to a welcome that seems as poignant as any parting. "I put out my hand to shake that of the woman with premature streaks of gray hair . . . who I thought might be my aunt, but who, as she put her arm around me, I realized was my mother."

Mr. Bailey's book is dedicated "to those who sent us and to those who took us in."