As the King begins outpatient treatment after his cancer diagnosis, and the Princess of Wales is convalescing until Easter, last year’s busiest royal, Princess Anne, just got busier.

Along with her sister-in-law, the Queen, they have been unofficially labelled “Royal MVPs” by Vanity Fair magazine.

On February 6, Anne – who was given the official title of the Princess Royal by her late mother, Queen Elizabeth, in 1987 – covered 655 kilometres across the UK in 11 hours to carry out five official engagements.

Two were on behalf of the King.

From her 280-hectare Gatcombe Park home in Gloucestershire to Windsor, to Nottingham and back to London via helicopter, she reportedly didn’t even .stop for a 20-minute sandwich break.

“Anne hasn’t put a foot wrong. In her looks, in her voice, and especially on horseback, she is the best living reminder we have of [Queen] Elizabeth II [who died in September],” wrote Allison Pearson in The Telegraph this week.

“Undoubtedly, she has everything it takes to take the strain of the Crown awhile till the man who regards her so highly is well enough to pick it up again.”

Princess Anne makes rugby union referee Sara Cox a Member of the Order of the British Empire. Photo: AAP

‘Anne has no ego’

In December analysis by The Telegraph of public events and official meetings based on entries published in the Court Circular showed Anne, 73, “was the most industrious member of the family”.

She carried out 457 engagements while the King was ranked second, with 425 royal engagements. Their brother, Edward did 297 engagements.

She earlier won that honour in 2017.

Anne survived a kidnapping attempt in 1974, competed at the 1976 Olympic Games where she rode the late Queen’s horse, was nominated for a Nobel Peace Prize in 1990, and spearheaded the London Olympics in 2012.

So how did her Tuesday shape up?

Anne’s day began at 9.30am with a helicopter ride to Windsor Castle to undertake an investiture on behalf of the King, the Mirror diarised.

She started at 11am and finished at 1pm, where she honoured rugby referee Sara Cox, Elisabeth Murdoch, conductor Ivor Bolton, tenor Nicky Spence and wheelchair rugby league player James Simpson.

“After her trip to Windsor she was reportedly scheduled in for a 20-minute sandwich break, however she did not eat it and instead flew straight up to Nottingham,” wrote the paper.

At 2.10pm she met occupational therapists in Nottingham, returned to London where that night at the Science Museum she handed out the Queen Elizabeth Prize for Engineering on behalf of the King.

Buckingham Palace has said Queen Camilla, 76, will also continue with a full program of activities, however, she has no official diary listings on the royal website, royal.uk.

“She is now the Queen and she will have to balance the two issues of responding to [the King’s] needs as his partner and the demands of being the most senior royal,” royal commentator Peter Hunt tells The Guardian.

“Collectively across the palaces, they are going to have to look at their diaries and work out – can they cover all the events there are demands for, or are they going to have to reduce them?”

It is a “moment of stress” for the monarchy, “because they probably don’t have a clear idea in terms of a time frame of when he will resume public duties”.

Between now and the end of February, Anne has 26 royal engagements while Edward is the only other royal listed, with six official engagements.