Mr. Roberts, the author of "The Storm of War," is a trustee of the Margaret Thatcher Archive Trust.

Reagan and Thatcher
By Richard Aldous
Norton, 342 pages, $27.95

How genuinely close were Ronald Reagan and Margaret Thatcher? In the popular imagination, of course, they were as close as were Churchill and Roosevelt, or Kennedy and Macmillan, or George W. Bush and Tony Blair—possibly even closer since their political ideologies coincided as well. Yet as Richard Aldous shows in "Reagan and Thatcher," a well-researched, well-written and revisionist double portrait, very often the day-to-day policies they pursued diverged significantly. The result was "a more complex, testier relationship" than we might hitherto have thought.

It is clear from the outset that Mr. Aldous, a distinguished British-born professor of history and literature at Bard College, is not some ax-grinding academic with an animus for the two greatest giants of postwar Western statesmanship. He obviously admires both leaders but merely wishes to point out, often through the use of recently declassified documents, that theirs was on occasion "a fractious alliance" rather than what Mr. Aldous calls "the merely love-struck political marriage of contemporary myth."

In the 1990s, Sir Nicholas Henderson, the former British ambassador to Washington, said to the Labour Party politician Tony Benn: "If I reported to you what Margaret Thatcher really thought about President Reagan, it would damage Anglo-American relations." The prime minister and president certainly seemed to have had at least one major clash every year of the eight they shared in office....