“In 1953, Britain was a very deferential society,” said Vernon Bogdanor, an authority on the constitutional monarchy at Kings College London. “Now, it’s a competitive society, based on people who’ve earned their position through achievement. Therefore, the monarchy is bound to attract more skepticism.”

Buckingham Palace is sensitive to the changing attitudes. It has cut back the procession route between the palace and Westminster Abbey from that taken by Elizabeth in 1953. That has the benefit of sparing central London from gridlock while also ensuring that the crowds lining the streets do not look sparse.

The ceremony itself has also been modified to account for a more diverse ecumenical country. Though many of its rituals still date back more than 1,000 years, the archbishop of Canterbury, the Most Rev. Justin Welby, who will preside over the service, has added several innovations to make it more inclusive.

Leaders of non-Christian faiths will present Charles with items of regalia that are not Christian in nature. The archbishop will invite millions of people from across the nation and Commonwealth to pay homage to the king, a rite that was reserved for the hereditary aristocracy at Elizabeth’s coronation. And before he leaves the Abbey, Charles will pause for a greeting from a group of non-Christian religious leaders.

For some expatriates living in Britain, the “soft power” of the monarchy cannot be underestimated. But appealing to a younger, more diverse population is a longer-term project than a single ceremony.

“I think that they have a strong brand, as a monarchy, and if they translate that into value to British society, then it’ll be fine,” said Marta Sauri Lopez, 36, a native of Spain who works for a private equity firm in London. “Probably the Commonwealth has a lot to say there,” she continued. “So, if the monarchy does manage to maintain the Commonwealth as unified, that’s a massive bonus.”