The Duke and Duchess of Cambridge's first port of call on their royal train tour was Edinburgh in Scotland.
Prince William and Kate pulled into Edinburgh Waverley station to the sounds of a piper playing Christmas songs including Jingle Bells and Santa Claus Is Coming To Town.
The duke was the first to step out of the Royal Claret-coloured carriages, adjusting his face mask as he did so, followed by Kate.
They were welcomed to the city on the platform and chatted briefly, before thanking the piper and leaving the station to make their way to their first engagement.
READ: Kate Middleton's sweet secret calls revealed: 'Call me Catherine'
WATCH: William and Kate surprise school children in Berwick-upon-Tweed with reindeer visit
The couple will call at stops in England, Wales and Scotland between 6 and 8 December, where they will meet frontline workers, volunteers, care home staff, teachers, schoolchildren and young people to hear about their experiences during 2020.
William and Kate enjoyed a musical start to their royal train tour as Shakin' Stevens performed his hit Merry Christmas Everyone at Euston station before they departed on Sunday.
MORE: The Queen's royal train secrets revealed
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The Cambridges met frontline workers from the Scottish Ambulance Service in Newbridge, Edinburgh, during their first engagement of their royal train tour.
The couple thanked the staff for their incredible efforts during the coronavirus pandemic.
The visit coincided with the announcement that William and Kate have become joint patrons of NHS Charities Together.
Ian Lush, chair of NHS Charities Together, said: "This is such an honour for our organisation and for all the NHS charities across the UK.
"The involvement of Their Royal Highnesses will inspire the public to do even more to support the amazing NHS staff and volunteers who have done so much to keep us safe and well this year.
"We can't wait to start working with the duke and duchess, the potential is so exciting."
Kensington Palace said William and Kate's visit on Monday had added poignancy as it falls on the day the Scottish Ambulance Service remembers a colleague lost to Covid-19.
MORE: Kate Middleton's festive tartan outfit brought the Christmas joy
It also emerged during the visit to the Scottish Ambulance Service response centre that William and Kate had sent a special bouquet of flowers to the family of a veteran paramedic, who died last month after he re-enlisted in April four years after his retirement.
Rod Moore, from Falkirk, died aged 63 after contracting coronavirus.
His funeral was due to take place during the royal visit.
A spokesman for the ambulance service said: "I know that Rod’s family greatly appreciated the flowers sent on behalf of the royal family. It was a lovely gesture."
The Duchess, in a Liberty print face covering, was dressed in a repeat powder blue Catherine Walker coat and black gloves, while William was wearing a navy jacket and a tartan scarf, as they arrived in Edinburgh.
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William and Kate's second visit of the day was to Berwick-Upon Tweed in Northumberland, where they met teachers and pupils at the Holy Trinity Church of England First School.
The Duke and Duchess thanked staff for their work over the past year, including their efforts to keep schools open for vulnerable children and the children of key workers.
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The Cambridges had a special festive treat for school pupils in the form of reindeer, a visit which the couple had arranged for the children.
William and Kate were in their element as they chatted to pupils from the primary school, who wore antlers and Santa hats for the lunchtime visit.
The Duke and Duchess sanitised their hands as they entered the school grounds, a short drive from Berwick railway station.
After the visit, headteacher Nicholas Shaw said: "It has been fantastic and the children loved it.
"We feel honoured to have been chosen and appreciate they are taking the time to think about teachers and the work that has been going on in schools.
"It has been a challenge during lockdown, a lot of new skills have been learned.
"We stayed open throughout for children of key workers and vulnerable children."
Rent a Reindeer owner George Richardson took along Chaz, Crackers and her six-month-old calf Echols, and told William and Kate about caring for them and how coronavirus has affected his business.
Mr Richardson, who is based in Cold Hesledon, County Durham, said the booking by the palace had been “top secret".
He said: "We got a phone call out of the blue two weeks ago. They asked us to bring a reindeer for the royal visit and we were happy to oblige."
William and Kate's third stop on Monday was Batley Community Centre in West Yorkshire.
The couple met volunteers from the centre who have supported elderly members of the community throughout the pandemic by sending cards, having regular phone calls and dropping off shopping, food bags and activity packs.
William and Kate also met Len Gardner, a local resident with whom the Duchess has been chatting on the phone after she secretly volunteered through the NHS Volunteer Responder Check In And Chat scheme.
Kate has been reaching out to Len, 85, during the coronavirus pandemic. Kind-hearted Kate has made phone calls to the pensioner who is a full-time carer for his wife, and shared sweet details of her home life with children, Prince George, Princess Charlotte and Prince Louis, her love of pasta making and even sheep-shearing!
Len spoke about the pair's conversations to The Sun, and revealed how the Duchess had immediately dispensed with formalities on their very first call, telling him, "Call me Catherine."
William and Kate were even introduced to Len's wife Shirley during their visit to Batley in northern England.
There was time for a quick outfit change for the Cambridges, as William swapped his tartan scarf for an olive green one, while Kate stepped out in a repeat navy Hobbs coat for their third stop of the royal train tour.
For their final stop of the day, the Cambridges disembarked at Manchester Victoria station.
The couple visited FareShare in the city where they paid tribute to volunteers and organisations across the UK who have supported vulnerable families throughout 2020.
FareShare redistributes surplus food from food businesses to 11,000 charities and community groups in all four nations across the UK – including school breakfast clubs, community centres, homeless shelters and food banks.
In his speech at FareShare, William said: "I know you’ve had a particularly hard time over recent months, as has the whole of the north of England.
“I’m really glad we’ve been able to come and talk to some of you in person about how you’ve all been doing.
"Catherine and I felt that it was extremely important to visit just some of the heroes that have emerged this year to thank you for all that you have done.
"Whether that’s transport workers, paramedics, school teachers or indeed staff and volunteers like those of you online across the FareShare network, or here in Manchester tonight.
"You are the people that have not only kept our country going but have also helped warm all our hearts by showing us the very best of human nature."
At the end of their day, Kensington Palace posted a photo of the couple on Instagram sitting at a railway station, with the caption: "Where to next?"