Image copyright Reuters

Headlines questioning Prince William's work ethic have dominated the tabloids after he was pictured on a ski holiday while other senior royals attended a service with Commonwealth leaders.

"Throne Idle" and "Ice work if you can get it" were among the newspaper puns to greet the future king as he returned to the UK, having missed the Commonwealth Day events.

When he's not dad-dancing in Verbier or spending time with his young family, the Duke of Cambridge splits his time between royal duties, a part-time job as a pilot and his charitable work.

So far this year, the 34-year-old has attended royal engagements on 12 days, including a trip to south Wales, a gala dinner and an investiture at Buckingham Palace.

Royal engagements in 2017 (up to and including 10 March) 34 days The Princess Royal 29 days Prince of Wales 28 days The Queen

12 days Duke of Cambridge

10 days Duchess of Cambridge

9 days Duke of Edinburgh Getty Images

The record of these attendances is detailed in the Court Circular, which was last updated on 10 March and does not specify the hours of each event.

Nor does it take into account behind-the-scenes activity or preparation for royal events.

Since 2015, the prince has worked as a helicopter pilot for the East Anglian Air Ambulance Service. There, he works 9.5 hour shifts, clocking up an average of 20 hours per week - the salary for which is donated to charity.

Based on these hours and the royal engagements, Prince William will have worked the equivalent of 34 of the possible 53 working days in 2017 so far.

Earlier this year he announced he would be leaving his ambulance job in the summer to take on more royal duties.

By Peter Hunt, BBC royal correspondent

Image copyright Getty Images Image caption The Duke and Duchess of Cambridge at a service of commemoration earlier this month

This is not unfamiliar terrain for Prince William or indeed for his family.

To be found wanting in the eyes of the tabloids is an occupational hazard that has dogged them for decades.

When the prince decided to ski with his mates rather than leave early and attend a church service that mattered to his grandmother, he could have predicted that he would be judged to have made an error of judgement.

It was an error that he can regret at leisure.

But what he couldn't necessarily have predicted was that he would have remained headline news for so long. The future king is wary of the media. The newspapers are increasingly concerned at his attempts to bypass them and use social media instead.

The next test will come in the autumn when he becomes a full-time senior royal.

If by then there isn't a noticeable increase in his royal workload, there's a risk the tabloids will once again sit in judgement and once again find Prince William wanting.

Read more from Peter Hunt

In 2016, Prince William clocked up 80 days of royal engagements - well behind the busiest member of the royal family, Princess Anne, with 179 days of engagements.

Prince Charles, 68, came second with 139 and the Queen, 90, matched her grandson with 80 days.

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Despite denouncing the work-shy claims as "absolute rubbish" and "grossly unfair", royal commentator Richard Fitzwilliams said the headlines were "irresistible" for the tabloid press.

"It's an unfair perception that the photographs reinforce," he said.

Prince William has said criticism of being work-shy was not something he ignored, but not something he "took completely to heart" either.

Image copyright Reuters Image caption Prince William works about 80 hours a month as a co-pilot with the East Anglian Air Ambulance

Prince William is patron or president to 23 organisations, including the Royal Foundation of The Duke and Duchess of Cambridge and Prince Harry.

Not all the work he does to fulfil these roles is classed as a royal engagement.

Centrepoint - the youth homelessness charity of which the Prince has been a patron since 2005 - said the royal visits hostels publicly and privately, volunteering alongside staff and regularly meeting with the Centrepoint parliament.

Chief executive Seyi Obakin, said: "Within the last three months, he has publicly and actively supported our plans to create a national helpline for homeless young people.

"Last month, he launched with us the Centrepoint helpline."

Image copyright Getty Images Image caption The Duke and Duchess of Cambridge and Prince Harry race during the Team Heads Together London Marathon Training Day in February

Prince William has also campaigned vigorously against animal poaching. At an international conference in November he called on the UK government to pass a total ban on the domestic ivory trade.

This week, the Cambridges are visiting Paris and in July, the royal couple are due to make an official visit to Germany and Poland, at the request of the Foreign and Commonwealth Office.

Kensington Palace declined to comment when contacted by the BBC.