The King's support for the UK farming sector has been highlighted as he celebrates his 77th birthday today (November 14).
King Charles has now overtaken George II to become the fifth longest-living British monarch, despite only being in the third year of his reign.
The longest living monarchs were Queen Elizabeth II, Queen Victoria, King George III and King Edward VIII - who abdicated in 1936.
The Royal Countryside Fund said: "All of us at The Royal Countryside Fund wish our Royal Founding Patron, His Majesty The King, many happy returns on his birthday.
"As we celebrate 15 years since he created his Countryside Fund to support farming families and rural communities, his vision for a thriving countryside continues to inspire our work in building a real future for rural Britain."
In a written message for this year's National Harvest at Westminster Abbey, King Charles said his 鈥榟eart went out to those who were struggling' following a difficult year.
"It is the time of year to give thanks to the custodians of our land in a tradition that stretches back centuries, yet remains ever relevant.
"Their labour is the foundation of our food production, the heartbeat of rural communities and vital to the protection of the natural landscape we all treasure so dearly," he said.
"The particular resolve and resilience they have demonstrated through the challenges of our changing climate in recent years deserves our utmost admiration and gratitude - particularly in a year in which the weather has made growing anything so very difficult.
"Our hearts go out to those who are struggling especially, as winter approaches, those with livestock."
