The Duchess of Cambridge is recognised around the world but one little boy struggled to identify her during a royal visit to Orkney

Kate was asked “are you the prince?” when she and husband William chatted to a group of nursery school-age children after being shown one of the world’s largest floating tidal power turbines.

The duke and duchess were ferried by a Royal Navy vessel half a mile off the coast of the Orkney Islands to see the vast 680-tonne machine, which can generate enough electricity to power 2,000 homes and is undergoing testing.

As a mark of good luck the couple poured Scapa Whisky over its two 20-metre long rotor blades and ventured inside the 72-metre long Orbital O2.

When they stepped back onto dry land they took time out from their busy schedule to crouch down and chat with children from Glaitness Nursery, in Orkney’s main town of Kirkwall, who said they were desperate to meet “a real prince and princess”.

But one little boy pointed at the duchess and asked “Are you the prince?” and she replied: “No, I’m the Duchess of Cambridge” adding “Lots of people call me Catherine”.

William struck a chord with some of the young boys who were keen to show off their trainers, and one in particular could not quite hold in his excitement and said to the duke “Well, you must be the prince”.

The couple spent the day in Orkney and began by thanking medical staff for their efforts during the pandemic as they officially opened the islands’ £65 million Balfour Hospital.

William and Kate were greeted with cheers and rounds of applause from well-wishers and nurses at the start of their hospital tour – their first official visit to the remote Scottish archipelago.

The couple are making an extensive tour of Scotland in William’s role as Lord High Commissioner to the General Assembly of the Church of Scotland.

During their visit to the Balfour Hospital in Kirkwall, William praised trauma nurse Dr Tariro Gandiya: “It must be reassuring to know we are all in this together.”

Kate added: “Well done”.

The Cambridges are known by their Scottish title the Earl and Countess of Strathearn when north of the border, and Kate wore a Strathearn tartan scarf and a coat by Massimo Dutti for the visit.

They were given a private tour of the hospital which was the biggest construction project on the island since its cathedral was completed in 1168.

Before setting out for the giant turbine they met Neil Kermode, managing director of the European Marine Energy Centre (Emec) a leading facility for demonstrating and testing wave and tidal energy converters.

Mr Kermode told the Cambridges: “It is nice to know people care.

“I genuinely think we have something special here for the whole nation.”

William, who has launched his decade-long £50 million Earthshot Prize to recognise initiatives that help “repair” the planet, replied: “You should enter the Earthshot Prize.

“You still have 10 years.”

Emec also takes locally produced hydrogen and converts it back to electricity and the duke and duchess were shown its fuel cell and hydrogen storage trailers on the pier.

William asked: “Anything we can do to help in the future?”

He added: “Hopefully at the end of the year we will have some ideas (about Earthshot).

“I have seen a few of them and they are excellent.”