Friendship is an unappreciated relationship in political history, and perhaps that’s unsurprising: The more powerful the person, the harder it is to have one true friend.

To Queen Elizabeth I, Robert Dudley (1533-1588) was that one true friend. Their story is well told in historian Robert Stedall’s new book “Elizabeth I’s Secret Lover,” a well-researched account of their complicated relationship. If you finished Hilary Mantel’s “The Mirror and the Light” and are wondering what happened next to the blood-drenched Tudor clan, this could be the book for you.

Stedall begins with the last years of Elizabeth’s father Henry VIII, his death and the succession of his son Edward VI to the throne. Elizabeth, Edward’s half-sister, was declared a bastard after her mother Anne Boleyn was executed, and she kept a low profile, occupying herself with learning, sport and court life. It was there that she first met Dudley; as children they had the same teacher in the court school.

In the aftermath of Edward’s death at age 15, terror reigned as Elizabeth’s sister Mary Tudor, a Catholic zealot, assumed the throne. Both Elizabeth and Robert were in jeopardy — Elizabeth as a royal rival, Dudley tainted by his father’s plot to block Mary’s coronation and place a Protestant monarch on the throne. Dudley’s father, the Duke of Northumberland, was executed, and Elizabeth and Robert narrowly survived Mary’s brutal purges.

After Mary’s death Elizabeth gained the throne, and after Robert’s first wife died, there’s little doubt that they became lovers. There was abundant chemistry — Robert was a lady killer, 16th-century version. But theirs was primarily a great and loyal friendship. While they fell out with one another many times, they were at heart soul mates. They loved politics, and horses, and pageantry — one weekend-long fete thrown by Robert for Elizabeth became the basis of Shakespeare’s “A Midsummer Night’s Dream.”

After the death of his first wife Robert longed to marry Elizabeth, but her advisers pressed her to cement a geopolitical alliance by marrying a royal foreigner. And who could blame her for steering clear of marriage? Stedall writes that her “parents’ marriage had shown her that there was safety in being courted but risk, if the marriage fell out of love.”

When a courtier complained about rumors swirling around her and Dudley, Elizabeth replied that while she valued her reputation, “in this world, she had had so much sorrow and so little joy!” Their affair ended but the friendship endured. Elizabeth showered gifts and titles on Dudley, from Master of the Horse to Chancellor of Oxford University. He repaid her a hundred times over, carrying her standard in politics and war.

Stedall has an engaging no-nonsense writing style, leavened with a wry humor. His commitment is to the facts, and it can be challenging to follow the alliances and misalliances, as Spain, France and England vie with each other for control of Europe. But all in all, this story practically tells itself. It offers confirmation, if we needed it, that the story of England’s Tudors will never, ever grow old.

 Mary Ann Gwinn is a book critic in Seattle.

Elizabeth I’s Secret Lover
By: Robert Stedall.
Publisher: Pegasus Books, 368 pages, $28.95.