Elizabeth died aged 96 on Sept 8 at Balmoral Castle leading to 10 days of national mourning and condolences and tributes from across the world for her record-breaking 70-year reign.

At 74, King Charles became the oldest sovereign yet to be crowned at London's Westminster Abbey, after a lifetime as heir to his late mother Queen Elizabeth II.

All the stops have been pulled out for the biggest display of British pomp and pageantry in decades, outstripping the queen's state funeral last September.

The cost of the coronation has been kept under wraps and the total sum is unlikely to be revealed until after event.

The congregation at London's Westminster Abbey will comprise Nobel Prize winners, religious representatives, and heads of state and foreign ministers, the palace says.

The introduction of the new oath is one of the changes to the centuries-old ceremony, which the palace wants to evolve, particularly to reflect the country's diversity.

During the visit, Charles will address issues facing both countries such as sustainability and the Ukraine crisis, as well as commemorate the past, according to Buckingham Palace.

As well as an embarrassment to French President Emmanuel Macron, the postponement is a disappointment for Charles, taking the gloss off his first international engagement since succeeding his mother Queen Elizabeth in September.

Current polymer banknotes carrying the queen's portrait will remain legal tender which can continue to be used.

The Counsellors, who can act on behalf of the monarch in his absence to carry out all but his most key roles such as appointing a new prime minister, are selected from his spouse and the four adults next in line.

Domestically, Charles is less popular than his late mother, who maintained highly favourable ratings throughout her record-breaking seven-decade reign.

The king and queen are expected to have an audience with Britain’s King Charles III at Buckingham Palace.