I think there's an argument to be made that writing a persuasive, well-written and interesting history book makes you an historian, whether you're academically trained in history or not. For the sake of argument, however, if we called 'non-historians' all those who didn't have a history degree, then journalists have often made good attempts at writing history. They can use their investigative and analytic skills that have been utilised and honed in modern media to create works of history that are also made highly readable because of the author's journalistic background.

Probably the best example of this would be Simon Winchester, a journalist who studied geology at university. He has delved into a variety of historical topics, from the history of the Oxford English Dictionary in The Professor and the Madman, to natural disaster history in Krakatoa, to early American history in The Men Who United the States.

Bill Bryson's "at home" was a great read, his enthusiasm comes through well in his writing and he has a knack of focusing on the people behind events.

George Orwell's Homage to Catalonia is a great autobiographical work about his experiences as a POUM volunteer in the Spanish Civil War. Even without caring about the history, it's a really interesting read.

Of course, like all autobiographies, it only tells a snapshot of the greater story, and Orwell had strong political views which very likely influenced his telling of events. I wouldn't recommend using it as an exclusive source for the life and times of people/soldiers in wartime Republican Spain.

I enjoy reading Karen Armstrong. She writes about comparative religon, so there is a big historical component. 'A History of God', 'The Great Transformation: The Beginning of Our Religious Traditions' and 'The Battle for God: Fundamentalism in Judaism, Christianity and Islam' are three of her books that I've enjoyed.

I recently read a book called Lest Innocent Blood be Shed by Philip Hallie.

It's without a doubt one of the best books I've ever read. The subject is a small village in Vichy France during WWII that saved hundreds of Jews from the French police and later the Gestapo.

Hallie is not a historian, rather a philosopher but he did a lot of primary research on the subject and the book is a phenomenal tale of people helping other people.

"A Place of Greater Safety" by Hilary Mantel is, I think, one of the best and most readable books on the French Revolution, specifically on the careers of Danton and Desmoulins. It is simply brilliant.

On Revolution by Hannah Arendt, which is about the French and American revolutions. She gets a lot of stick from historians because it's deemed too philosophical and not rigorous enough for history proper. However, there are few writers out there that can get you to question your received beliefs in the way that she can. [The text is here if anyone's interested] (https://archive.org/details/OnRevolution).

The Second World War and A History of the English-Speaking Peoples by Sir Winston Churchill

I really like the way he writes

Nancy Mitford, one of my favorite historians, began her career as a British socialite and fiction writer. In her later life she moved on to non-fiction and became a respected writer of popular history and royal biographies.

From Wikipedia:

Mitford's informal style was remarked on by the literary critic Cyril Connolly, who wrote that her facility for transforming unpromising source material into readable form was a skill that any professional historian might envy. The historian Antonia Fraser considered Mitford an important contributor to the "remorseless process by which historical and biographical sales have soared since 1950".

Her fiction is entertaining, but my two favorite history books by her are Madame de Pompadour and The Sun King. If you're interested in the French royal court at the palace of Versailles, put those two on your reading list!

Emmerich Talos wrote one of the standard books on Austra Fascism. He's a studied political scientist.

For South African history, I'm a fan of Max du Preez's two books, Of Warriors, Lovers, and Prophets and Of Tricksters, Tyrants, and Turncoats. They include stories from across the centuries of South Africa's history, and read like books of short stories. He comes from a journalism background, and while he gets the history parts right, he also speculates about motives and psychology. Very interesting and entertaining reads.

Charles C. Mann wrote "1491: New Revelations of the Americas Before Columbus". He's a journalist (mostly science) by trade but I think that can be an advantage when writing tertiary material in large part because when something is controversial (like estimates of the population of the pre-Columbian Americas) he presents the range of thought on the issue. The book has generally gotten a thumbs up on this sub so I infer that it's reasonable accurate.

I know some historians and anthropologists object to the "New Revelations" part of the title because they're not very new in academia. What Mann meant though is that the progress that's been made in pre-Columbian studies in the last few decades hasn't made it into K-12 textbooks or popular knowledge.

He also wrote "1493: Uncovering the New World Columbus Created" which wasn't as eye opening to me, but is still very much worth a read.