Ms. Markle has “got to be swotting,” he added, using British slang that, as she will some day come to understand, means “to study assiduously.”
She is refreshingly open about how little she knows about her future adoptive country, let alone the British royal family.
In her first interview with Prince Harry, shortly after their engagement was announced on Monday, Ms. Markle confessed that she had not been wholly aware of her fiancé’s royal lineage before meeting him. A mutual friend had set the pair up on a blind date, she said, adding, “The only thing I asked her was, ‘Was he nice?’ ”
The exam she will take is known officially as the “Life in the U.K. Test,” and it is required for anyone settling in the country or seeking to become a citizen (and, therefore, a subject of the queen).
Before taking the test, applicants must have been living continuously in Britain for at least five years and must pay an application fee of about £1,200 — that’s $1,600 in the sort of currency Ms. Markle best understands.
A spokesman for Kensington Palace insisted that she intended to follow the process the same way as any other “American marrying a British citizen.” Takers of the exam have 45 minutes to answer 24 multiple-choice questions about British traditions, customs and history, all of which are based on information in an official handbook published by the Home Office.
Apart from Ms. Markle, there has been a spike of interest in the exam as debates over identity have mushroomed after Britain voted last year to withdraw from the European Union, a process known as Brexit. That referendum focused mostly on immigration, and many voters who support Brexit say British culture is being diluted because of the bloc’s policy of open borders between member countries.
In the 18 months since the critical vote, there has been much soul-searching across the island about what it means to be British. The questions on the citizenship test, many Britons say, do not go far toward settling the issue.
In addition, they say, the quiz is unfairly difficult, an assertion that was borne out in a scattershot survey of Britons one recent afternoon that found many struggling to answer sample questions correctly.
“A what?” Peter York, a prominent social commentator, exclaimed. “What is the Vindolanda?”
“Is that a real question?” he asked, perplexed. “That’s extraordinary.”
Mr. York, who blithely describes himself as an English “purebred” (“no Welsh, Scottish or Irish components in me”), found the questions unsettling. “I don’t think I’d be a British citizen,” he said. “If they can keep me out, they can keep anybody out.”
(The answer: Vindolanda was a Roman fort just south of Hadrian’s Wall in northern England. Mr. York also got the question about the Statute of Rhuddlan wrong; it led to the annexation of Wales to England.)
Mr. York said he preferred that foreigners study Alan Bennett, the prolific playwright; John Cleese, the comedian famed for the “Monty Python” series; and the punk band the Sex Pistols.
Gemma Page, 26, said British identity “comes more from ideas like tea and fish and chips.” Her husband, Liam, said British identity “isn’t a matter of how much you know.”
Britain “is a mongrel country,” he said. “Take tea and fish and chips. Tea comes from India and chips from Ireland. The only thing we can claim is the fish, and that’s because we’re surrounded by water. Being British is the values you hold. We try to be tolerant. We have free speech.”
George Jupe, 87, a Brexit supporter, said being British was a question of feeling. “But what makes you feel it, heaven knows,” he said, taking leave with a lively “Cheerio!”
According to a 2014 survey by YouGov, the pollster, more than half of 18- to 24-year-olds and a third of 25- to 39-year-olds failed the citizenship test. Some respondents answered that Hawaii was part of Britain and that National Insurance was used to pay for supermarket home deliveries.
Even some members of the Oxbridge-educated elite have demonstrated some surprising gaps in knowledge of the motherland. In 2012, David Cameron, then prime minister, told David Letterman that “Rule, Britannia!” — a rousing patriotic song often associated with Britain — was written by Edward Elgar. (It was Thomas Arne.)
The former leader also admitted to having no idea what Magna Carta, the cornerstone of the British legal and political system, actually stood for. (It means “Great Charter.”)
The test “is pointless,” said Michael Odell, the author of “The ‘Call Yourself British?’ Quiz Book.” He wrote the book because his publisher, a Dutch citizen, was so upset at failing her British citizenship exam that she commissioned him to look into why it was so difficult.
The civil servants who come up with the questions are “completely out of touch with applied British history and culture,” Mr. Odell said, as he sat putting together a mock exam designed for Ms. Markle, to be published by a British newspaper the following day.
“Whitehall boffins are trying to demarcate areas of knowledge and culture, trying to distill them into British identity, which is kind of amorphous,” he added, using a British term for a nerdish expert.
And in spite of an abundance of arcane historical information, Mr. Odell said, there were few questions involving minorities. In one test, he said, there was only one related question: “Who was the first person to introduce curry in Britain?” (It was Sake Dane Mohamed, in 1810, who also brought shampoo to Europe.)
A more recent test, however, asked a couple of questions about the Vaisakhi festival, which marks the Sikh New Year, and the Muslim religious holiday Eid al-Fitr. (The answer to two habits that may start a fight with your neighbor in Britain? Putting out garbage bags when it’s not trash day, and keeping an untidy garden.)
Whatever the questions, at least three-quarters of them must be answered correctly.
“If Meghan Markle can’t get past me,” Mr. Odell deadpanned, “the wedding is off.”