The Prince of Wales is preparing for the day his eldest son will take over the Duchy of Cornwall after spending 50 years in charge of the estate.

Prince Charles hinted it was time for new blood in an interview for a two-part documentary series commissioned by ITV to mark the anniversary.

The first episode, airing at 9pm on Thursday, October 24 on ITV, offers a behind the scenes glimpse into the Duchy of Cornwall which covers more than 130,000 acres across 23 counties.

The Duchy estate was established by Edward III to provide a private income for his son and heir to the throne Edward, later known as the Black Prince, and its purpose remains the same today.

During the 60 minute episode, Charles is seen living up to his reputation as a hands on duke - pruning, hedgelaying and celebrating his 70th birthday with tenants.

Charles took over management of the estate when he was 21 and hopes in his time at the helm he's supported its people.

"I hope we can help support you a little bit, which is what I've been wanting to do all these years," the prince said in the documentary.

The prince has been described by the Duchy of Cornwall's keeper of records Alastair Martin as "very hands on" in his role.

Mr Martin is also responsible for preparing the Duke of Cambridge who will one day inherit the estate from his father.

Charles said his eldest son has had time to prepare himself for his upcoming responsibilities.

"He's quite lucky because I found myself there at 21. I had a bit of baptism of fire really," Charles said.

"He goes and visits different parts of the Duchy of Cornwall, and so he is learning, I hope, as time goes by."

The Duke of Cambridge appears briefly in the episode and said he has started to think about how he will inherit the Duchy.

"Rest assured I'm not going to rock the boat. I'll do much the same as what my father's doing," William said.

The documentary follows Charles to all corners of the estate - from family farms, to the Isles of Scilly and his model village of Poundbury in Dorset.

Charles said the idea behind Poundbury was to build a community rather than "another housing estate" but acknowledges it was met with criticism.

"Everybody was against it, and in the end I was determined to stick to my guns," he said.

Farmers are the core of the Duchy with about 700 farming tenancies within the estate.

Charles notes how in his half a century as custodian he has watched as younger generations have taken over family farms, just like he took over as duke after the Queen's accession to the throne.

"For me the wonderful thing is the connection between my family and their families," he said.

His wife, the Duchess of Cornwall, also appears in the documentary and revealed how important the estate is to the prince.

"It's not just a business, I think it encompasses everything he is passionate about," she said.

The estate is a private portfolio of land, financial investments and property - including the Oval cricket ground in Kennington and 67,000 acres of Dartmoor.

There is no confirmed air date for the second episode, but it's expected to hit screens on October 31.