King Charles got into the festive spirit with an enthusiastically received visit to a Christmas market in the redeveloped halls of Battersea Power Station in south-west London.

A community choir was singing the carol We Three Kings as he arrived – and they had at least one real-life King there in person to listen.

“You must be frozen. You’ll need a stiff drink,” the King said to the singers, outside in the December drizzle.

The King also met Apple chief Tim Cook at the computer firm’s UK headquarters in the huge former power station building, before singer Raye gave them a seasonal serenade of “Holy Night”.

Much of the power station is now a glitzy mall and Christmas shoppers got more than they bargained for as the King appeared, walking past the window of Starbucks.

There can be something wistful about even the most cheerful carols – and it’s been a difficult year for the King, with his health problems.

But he looked cheerful here, talking to some rather gobsmacked stallholders under the Christmas lights. He always seems energised by the crowds, joking and chatting.

When he was being steered on to the next part of the trip, he still dived across for an impromptu meeting with shoppers, shaking hands and facing the wall of mobile phones.

The trip to the power station seemed to recharge him.

He was introduced to 90-year-old Rita Kelly, who had worked here in the 1950s when the turbines were pumping out power for the capital, and who said she was “honoured” to talk about her memories with the King.

“Working here was a very happy time,” she said. Although she said the King seemed to know about her “mischievous” side, when as a youngster she’d misguidedly tried to go upside one of the huge chimneys.

Not even Father Christmas would have risked that one.

The King visited the Curated Makers Market and saw the stalls for small traders and craftspeople. It was founded by Megan Jones, who has been supported by the King’s Trust, formerly known as the Prince’s Trust.

“People tend to go to big shops, but here they can talk to people behind the brand,” said Soophia Foroughi, who chatted to the King about her handmade jewellery, under her label Ava and Azar.

Natasha Kutrovatz, who sells her own jewellery, was delighted by the King’s interest in people making a living from handmade crafts. “As a parent, it’s a much more flexible way of working,” she said.

The 1930s power station once produced a fifth of London’s electricity, including supplying landmarks such as Buckingham Palace and the Houses of Parliament.

The link to Buckingham Palace had been discreetly labelled as “Carnaby Street” in the control room, in case anyone broke in and literally wanted to switch off the Palace lights, said a spokeswoman for the power station.

With the crowds and cameras for the King’s visit, it was probably louder inside the halls than when it was generating power.

It’s enough to shake Santa’s workshop, although in a designer outlet like this, the resident Santa is living in a “yurt”.

This huge cathedral of the industrial age remains an impressive sight – and the King’s mother, when she was still Princess Elizabeth, had come here in 1949 to see the power station operating.

The power station, built with six million bricks, is now filled with shops and places to eat and drink and the King looked up inside this cavernous post-industrial landmark. He waved back to some rather taken-aback shoppers, looking down from the layers of walkways above.

The boiler house is so big that St Paul’s Cathedral could fit inside.

The King is known to be interested in architecture and design – and this building, with its four chimneys looking like an upside down coffee table, was designed by Sir Giles Gilbert Scott, also responsible for the classic red phone box and Liverpool Anglican Cathedral.

There’s a strong sense of design for another business based in the power station – the technology firm, Apple, which the King visited after the Christmas market.

Some might see parallels between Apple computers and the monarchy – a bit expensive but with many dedicated fans who think it’s worth it.

The King went into the Apple headquarters to meet chief executive Mr Cook and was shown an example of the firm’s artificial technology, which can turn a few squiggles into a fully-fledged illustration.

The computer company has worked with the King’s Trust to help provide young people with digital skills and the King unveiled a plaque.

Cook praised the King’s “lifelong commitment to philanthropy and the betterment of humanity”.

There’s a message about changed times in how it’s Apple that now occupies these old buildings. This power station once used a million tonnes of coal a year, dug up in coalfields in Wales and northern England. It is tech-firms like Apple and designer shops that now fill the huge halls.

And given how much the King has been photographed by mobile phones, there can few people in the country who have seen as many iPhones close up.

At the end of the visit, drawings by children at a nearby primary school were projected on to the giant chimneys, climbing up into the evening sky. As the King left there was more music, with a performance by singer-songwriter Raye.

After all the Christmas trees and conversations, maybe it was time for his own stiff drink.