Although Britain’s Queen Elizabeth II is the core character of Netflix’s “The Crown,” the recent arrival of Season 4 introduces Lady Diana Spencer, the teenage nursery teacher turned princess whose rise to global superstardom unexpectedly eclipsed the popularity of her husband, Prince Charles — the heir to the throne — and the sovereign herself. Viewers eager to know more about the House of Windsor’s history might start with these five books.

HRH: So Many Thoughts on Royal Style,” by former Wall Street Journal features reporter Elizabeth Holmes, explores the fashion of four royal stars: the queen; Diana; Catherine, Duchess of Cambridge; and Meghan, Duchess of Sussex, as the actress Meghan Markle became known after her 2018 wedding to Prince Harry. Essays give a biographical overview of each woman, followed by several pages of pictures with captions and brief texts on different events and outfit trends. At times, the quips and asides can be jarring; what works as comment bubbles on Instagram (“HERE FOR IT!”) doesn’t always transfer to print. Although Holmes clearly did her homework, and brings together sartorial studies that are usually distinct, avid followers of royal fashion will find little fresh information.

Holmes argues that royal wardrobes are “a treasure trove of meaning” and “one way these women speak.” Royal outfits are not just pretty clothes but homages coordinated to specific outings. There are visible signals — maple-leaf details in Canada, a poppy print in California — with hemlines and sleeves tailored to accommodate bending toward children or reaching into crowds. There are also invisible touches, such as brands selected to highlight industries or causes.

In Holmes’s telling, the queen sought to build a uniform that would make her recognizable and appropriate yet never trendy. This helped the young sovereign be taken seriously in a world of mostly male leaders. The consistency of her wardrobe — with her signature coats and hats infused with sharper colors and fits in recent years by dresser Angela Kelly — is an outward manifestation of Elizabeth’s approach to reigning: emphasizing the monarchy, not the monarch.

Since most royal women say little publicly, reading anything but the most superficial messages into their fashion raises questions of projection: Is the message theirs or one that viewers think we see? Diana is the outlier, as the princess spoke with journalists in addition to sending sartorial signals. (Remember the infamous sweater with the black sheep? Holmes notes that she had at least two.) The book is strongest when Holmes studies the clothes. Fortunately, there are lots of clothes and accessories — including, yes, tiaras — to assess.

Readers seeking a broader historical take on the Windsors might try The Crown, Volume 2: 1956-1977,” published last November. Written by historian Robert Lacey, a consultant to the show, the book is an official companion to the Netflix series covering Seasons 2 and 3. It provides a contextual history — enough details on economic crises and the political fortunes of various prime ministers to test even the most loyal fans. Helpfully, the book specifies points where the show diverges from fact. For example, calendars and other information indicate that Prince Philip “can never possibly have met” Russian ballerina Galina Ulanova, whose portrait the queen finds in her husband’s bag in Season 2. (That suggestion of a possible affair is briefly referenced in Season 4 as well.) Princess Margaret and her husband, Antony Armstrong-Jones, traveled to the United States, as seen in Season 3, but Margaret’s role in securing a financial bailout for Britain is fictional. Other tidbits: The boarding-school competition Prince Charles struggles to complete did not exist; and the queen did not visit the United States in 1968 with her longtime friend Lord Porchester, though he was later manager of her racehorses.

Another approach to royal history can be found in Prince Philip Revealed,” published last month by Ingrid Seward, longtime editor of Majesty magazine. In examining the life of the queen’s 99-year-old husband — well known for his acerbic comments — the book touches on various events: Philip’s 1947 wedding to then-Princess Elizabeth, her transition to queen (and his efforts to support his wife “without getting in the way”), Charles and Diana’s marital woes. Philip retired from public life in 2017, but his devotion to duty and his spouse remain evident.

For those interested in current-day drama, there is Battle of Brothers: William and Harry — The Inside Story of a Family in Tumult,” also by Lacey. The book, published last month, walks readers through the turbulent childhood of Princes William and Harry as they were exposed to the unhappy marriage of their parents, Charles and Diana, “who were more inclined to talk to the press than to each other.” Against the backdrop of much-publicized crises that aligned the brothers — and left both deeply distrusting of the media — Lacey traces them growing apart in recent years as William embraces his role as heir and Harry, the younger-brother “spare,” eventually opts out of official life.

As Harry got serious with then-girlfriend Meghan, a divorced American, William asked whether the relationship was moving too quickly. For brothers who had “never hesitated to tell each other exactly what they thought and felt,” Lacey writes, this became explosive: Harry suspected that William, as future king, was questioning Meghan’s suitability for marriage.

Lacey suggests that Harry and Meghan “developed an exaggerated idea of their own importance,” though he also argues strongly that Meghan, the target of racial bias and unfair media criticism, was ill-served by palace bureaucrats. He writes in detail about Christopher Geidt, a forward-thinking staffer to the queen whose 2017 dismissal — sought by Prince Charles and his brother Prince Andrew — blew an opportunity to think creatively about welcoming the first biracial royal and building on her strengths. Ultimately, Lacey offers no juicy insights into the brothers’ divide: “At the time of writing, no credible record exists of what William and Harry said to each other in these painful confrontations.” Translation: Diana’s boys, even if furious with each other, will not betray each other to the wider world.

Harry and Meghan’s views on palace life can be found in Finding Freedom,” a much-hyped book published in August by royal commentator Omid Scobie and journalist Carolyn Durand. Describing a toxic media environment and unbearable protocol that ultimately drove the couple to quit their official roles, the authors cite interviews with more than 100 aides, friends and others in the couple’s “inner circle” for their sympathetic account. (Although Harry and Meghan were rumored to have cooperated with the book, or allowed friends to do so, a lawyer for Meghan said in September court papers for a privacy lawsuit against a British newspaper that the book is “extremely anodyne” and contains inaccuracies.)

The easy-to-read narrative is far from an objective biography. It also effectively salts the earth for a return to Britain, where the couple quit Harry’s family business but, technically, not his family. Fans will hope that the couple have found both freedom and happiness in California.

Harry and Meghan’s departure from royal life inevitably stirs comparisons to his mother’s experience. Ultimately, Diana’s unhappy marriage and untimely death battered public opinions of the monarchy. In the latest episodes of “The Crown,” the introduction of Diana and the “Iron Lady,” Prime Minister Margaret Thatcher, promise palace intrigue as the queen, reaching her 60s in the 1980s, encounters unexpected competition for center stage.

Autumn Brewington is a Post opinions editor and former royal blogger.