LONDON — If one of the top duties of the royal family is to produce heirs, then Prince Harry and Meghan Markle, the Duke and Duchess of Sussex, are performing very well, thank you very much.

Kensington Palace announced Monday morning that the couple are expecting their first child in the spring of 2019.

Five months after their internationally televised royal wedding at Windsor Castle, Harry and Meghan continue to bask in the honeymoon glow of warm coverage in the notoriously critical British press — where the news of a royal baby on the way was met with shouts of joy and front-page headlines in the tabloids.

The American Markle has taken to her new job like a seasoned pro. She’s poised, she’s proper — and the queen reportedly loves her.

The ginger-haired Prince Harry, 34, is the grandson of Queen Elizabeth II. Markle, 37, is a former actress.

Their child, seventh in the line of succession, will be a great-grandchild of the queen and the Duke of Edinburgh. With Prince Charles, Prince William, Prince George, Princess Charlotte, Prince Louis and Prince Harry ahead in the line of succession, it is unlikely — given modern medicine and House of Windsor life spans — that the baby will ever be monarch.

But forget the throne; the arrival of Meghan and Harry’s kid will be huge news come March or April.

A spokeswoman for Kensington Palace said the duchess is “in good health.”

She added that Meghan’s mother, Doria Ragland, “is very happy about this lovely news, and she looks forward to welcoming her first grandchild.”

Reaction on social media was instantaneous — and giddy. Within minutes of the announcement, #RoyalBaby was trending worldwide.

Taking time out from crunch Brexit talks, British Prime Minister Theresa May tweeted: “My warmest congratulations to the Duke and Duchess of Sussex on the happy news they are expecting a baby in the Spring. Wishing them all the best.”

Woody Johnson, the U.S. ambassador to the United Kingdom, tweeted, “Happy news to wake up to on a Monday morning.”

Many tweets were congratulatory, others inquisitive. Some wondered whether the baby would be American or British or both. Some hoped they might get the birthday off  — Britons still fondly recall that they got an extra holiday for the nuptials of Prince William and Kate Middleton, now the Duchess of Cambridge.

In Britain, you can bet on almost anything, and bookies were quick off the mark to suggest possible names for the newest royal.

“Opening odds on name of Harry & Meghan’s baby,” announced the bookmaker Ladbrokes, which listed Victoria, Albert, Arthur and Diana as favorite names.

The couple touched down Monday morning in Sydney for a 16-day tour that begins in Australia — their first official royal tour. The trip follows in the tradition of Harry’s parents, Prince Charles and Diana, Princess of Wales, whose first royal tour was to Australia and New Zealand.

Speculation about a possible pregnancy mounted when the royal couple emerged from their Qantas flight from London. Markle held several large purple folders in front of her — the type of materials that might otherwise be handled by an aide.

Here are key moments from the wedding of Britain's Prince Harry and America's Meghan Markle at St. George's Chapel at Windsor Castle on May 19. (Sarah Parnass/The Washington Post)

The trip is their first overseas as a married couple and includes the other part of their job — performing “engagements” and supporting good works.

Since the wedding, the couple — well, let’s be honest, mostly just Markle — has been subjected to maximum scrutiny.

The tabloids actually employ lip readers, most recently to try (unsuccessfully) to suss out what Meghan said to Harry when she appeared to give him a gentle reproach at the weekend wedding of Princess Eugenie and tequila salesman/commoner Jack Brooksbank.

When Markle, attending her first solo engagement, was caught on camera closing her own (chauffeured) car door, the British press wigged out a little as it pondered whether she violated royal protocol.

Until further investigation revealed footage of Kate Middleton doing the same thing. So, basically, never mind.

Markle also brought much attention to her first solo project as a royal: She helped to launch “Together: Our Community Cookbook,” a charity cookbook with proceeds supporting victims of the Grenfell Tower fire tragedy. The book quickly became a bestseller.

The mixed-race American divorcée actress is generally viewed as just what the royal family needed — and she is also seen as keeping Harry on his toes.

The single asterisk has been the Markle family.

Markle’s father Thomas famously did not attend the wedding ceremony — after going to the trouble of posing for paparazzi pics — citing ill health. Harry’s dad Prince Charles escorted Markle down the aisle instead.

Since then, Thomas Markle has given paid interviews that have raised royal-watcher eyebrows, saying in one that his daughter would “be nothing without me” and that “I made her the Duchess she is today.”

Markle’s half-siblings, too, have made a spot of news. Samantha Markle, for one, compared Prince Harry to a ginger hamster and has called her younger sibling “narcissistic and selfish,” in part because the duchess has kept her at arm’s length. So, that kind of family.

Jennifer Hassan in London contributed to this report.