Future queen: Duchess of Cambridge, Kate Middleton, turns 40

Since marrying into Britain's most famous family in 2011, the former Kate Middleton has emerged to become one of the most popular royals - and a figure central to its future. Her image as a safe pair of hands, at a tricky time for the monarchy, was boosted at a televised Christmas carol concert in December.

Both Kate and William, who turns 40 in June, have been much more visible public figures since the start of the global health crisis. The couple have held video meetings with frontline healthcare workers battling the outbreak, which has claimed some 150,000 lives in Britain since early 2020.

As restrictions lifted, they have been seen at official engagements, from the glitzy world premiere of the new James Bond film to meeting world leaders at the G7 and UN climate change conferences. Kate has also pushed her own initiatives such as championing early years education and, with William, promoting mental health and protecting the environment.

The couple's former private secretary Jamie Lowther-Pinkerton told The Times newspaper that part of Kate's appeal was her polite, down-to-earth and unflustered nature. "She takes time to talk to people," he said, likening her to Queen Elizabeth II's own mother, who was a symbol of British resilience during World War II.

A lot of the focus on Kate since she and William started dating as students in Scotland was on her middle-class background. Despite attending one of Britain's top private schools, much was made of how she would fit in to the arcane world of royalty with its traditions and conventions.

Kate has, in public at least, given the impression of being eager to embrace royal duties, and unlike her sister-in-law, Meghan (right), given little away. In the British media, she has enjoyed favourable coverage, particularly since Meghan and her husband Prince Harry quit royal life and moved to the United States last year.

Nonetheless, Kate - known for carefully curated social media posts of family life - has encountered some brickbats, not least for her immaculate appearance. But she is clearly seen as a dependable figure in royal circles at a crucial time.

With the Queen now 95 and stepping back from public duties on health grounds, William's father Charles and his second wife, Camilla, have become more prominent. But with Charles now 73, his reign, when it starts, is already being seen as a transition to William and Kate's more up-to-date, empathetic, Instagrammable version of a venerable institution.