Cardiff, United Kingdom - King Charles III heads to Wales Friday for the last of his visits to the four nations of the United Kingdom as preparations for the queen’s state funeral gather pace.

With queues to view the coffin of Queen Elizabeth II lying in state reaching over four miles (6.4 kilometres) long, Charles and his three siblings -- Princess Anne, Prince Andrew and Prince Edward -- were due to hold a family vigil in front of the coffin.

The so-called Vigil of the Princes, with all four royals in ceremonial military uniform, will last for 15 minutes from 1830 GMT.

British officials on Thursday pledged “a fitting tribute” to the queen, who died last Thursday at the age of 96 after a record-breaking 70 years on the throne.

Her death has triggered an outpouring of emotion, with tens of thousands queueing for hours to pay their respects to the late monarch.

Charles, until last week the longest-serving Prince of Wales in history, was due to fly by helicopter to Cardiff early on Friday.

A spokesman for the king said he had a “lifelong commitment to the country’s people” and would have a private audience with the Welsh First Minister Mark Drakeford during his visit.

The king was “resilient and hard working” despite his loss, and “focused on leading the family, the nation and realm and the Commonwealth in mourning for Queen Elizabeth II”, the spokesman added.