His Majesty first visited the sawmill in 1999 when he was Prince of Wales and many employees are still with the company today to witness his second visit to the site.

The visit commemorated the completion of the sawmill’s extensive £15 million redevelopment programme that has taken place over the last five years.

His Majesty was given a tour of the site, including the mill’s flood defence system, timber processing plant and the kilns before being introduced to a number of long-standing employees, apprentices and student placements. His Majesty then signed the company’s visitor book and unveiled a plaque that marked the occasion before being presented with an engraved wooden bowl.

Tom Bruce-Jones, chairman of James Jones & Sons Ltd, said: “We were honoured to welcome His Majesty to our Aboyne site yesterday to demonstrate the extent of our recent sawmill investments and technology upgrades.

“We discussed the significant benefits of productive forestry acting as carbon sinks and the merits of continuing to meet and exceed annual planting targets across the UK. We were able to showcase the environmental advantages of UK grown structural timber products to support our collective views on building future houses sustainably.”

The King thanked “marvellous” workers for processing timber from Balmoral and said: “Well done everybody thank you very much for all the efforts you made. I hadn’t realised what an area you cover around the world, it depends on all the marvellous people who put so much into it.”

The visit came as James Jones & Sons announced that all timber and co-products supplied by the company will now be dual certified as FSC and PEFC.

This includes all timber delivered from that date, regardless of what date it was produced.

Graham Blyth, sales director at James Jones & Sons, said: “The dual certification offers our customers a greater choice when buying sustainable timber. The Soil Association, as our certification body, fully approved our ability to offer all our timber and co-products as dual FSC and PEFC certified. Our customers can continue to sell their timber as FSC certified but will now also have the choice to stock and sell as PEFC certified should their customers require this.”