Technology giant Sony welcomed the King to its site in south Wales, where he jokingly described it as “my factory”.

Charles’s visit to the Sony UK Technology Centre on Thursday marks 50 years of the company being based in Wales, for the last 30 in Pencoed.

He had visited the Senedd with the Queen earlier in the day.

As he was shown around he was presented with pictures of visits he and other members of the royal family had made, and joked that seeing a picture from his first visit in 1974 was “making me feel so old”.

The King packs a Sony HD system camera (Phil Noble/PA)

The King described the site as “my factory” to staff, having encouraged Sony to set up a site in Wales in the early 1970s while on a trip to Japan.

Charles showed a keen interest in the staff and their wellbeing, asking them how they liked working for the company, and saying he hoped they were getting enough holiday.

As he was shown around he finished the production of the 30,000th high-definition camera produced at the site, placing a sticker on the camera before boxing it up.

Charles also took an interest in sets of robotic arms, which were placing components on Raspberry Pi circuit boards – modular credit card-sized computers – and packed the fifty millionth produced.

Kimio Maki, representative director, president and chief executive of the Sony Corporation, told the King it was an “honour” to have him join them in celebrating 50 years in Wales.

He said: “This achievement is a testament to the enduring relationship between Sony and the Welsh Government and, indeed, the unwavering support from the royal household.

The King looks at robots on the production line (Phil Noble/PA)

“Your Majesty, I am reminded of your previous visit in 2014 when you remarked, ‘this is my factory’.

“Such an endearing comment speaks volumes and continues to inspire us to this day.”

Speaking after the King’s visit, Rob Wilson, Sony UK Technology managing director, said: “He was really, really interested about who was here 10 years ago when he last visited and what they were doing.

“Then the third thing he was interested in was how they were feeling, and their wellbeing.

“It was really, really encouraging, really lovely to see.”

Mr Wilson had also shown the King around on his previous visit.

He described the King’s claim that the factory was his as “tongue in cheek”, but said it was a “lovely link to our relationship with the royal family since we started”.

As he left, the King was presented with a flagship Sony Alpha camera, and Mr Wilson said he hoped he would take lots of pictures.