The estate made a profit last year of £21million from a diverse property portfolio which includes a B&Q site in Milton Keynes.
This first episode examines Charles’s life work as the longest serving Duke of Cornwall – referred to by his staff and tenants as “the boss”.
It visits the Duchy headquarters, adjacent to Buckingham Palace and the struggling farms on the Isles of Scilly. It also shows how young families are supported as they get into farming.
In the second episode, the focus is on transition as Charles, 70, suggests that one day he will pass running of the estate to William.
He said: “I can’t believe it’s 50 years of this, because it doesn’t seem possible. Because of course, it’s a lifetime, completely.”
Asked how he feels about the “succession” to William, he replied: “Confronting your own mortality is a very good thing for you, if I may say so, it’s quite good for the soul.” Emotionally, he watches William, 37, talking to a tenant farmer about the pressures of hill farming.
He said: “I couldn’t believe it. I was deeply touched and moved by what he [William] said.
“It practically reduced me to tears, it did really because I suddenly thought… well just hearing that from him, has made the last 50 years worthwhile.
“I want to be able to potter round, you know on a stick, in my dotage, saying gosh look at this, you know.”
William, who is already taking his future responsibilities seriously, added: “I’ve started to think about how I will inherit the Duchy one day and what I do with it.”
In the meantime, the young royal showed he is as flummoxed as everyone about the future under Brexit in an exchange with tenant farmer Mervyn Keeling.
He pressed William about the impact on hill farmers when EU subsidies disappear. William said he has met some of them and they were “worried”.
William later sought to reassure Mr Keeling saying: “I am very passionate about my farming.
“I just want to learn more about it and… if I can actually get my fingers into a bit more farming myself, then that’s the best way to learn, you see it all.”
The Prince revealed that his son George is “obsessed” with farming. The show also highlights many of Charles’s idiosyncrasies such as that he travels with his own marmalade and has an aversion to the colour yellow.
Princes Charles said he was mindful of the Duchy’s history. At a party, he said: “The wonderful thing about the Duchy… has always been that family association, going back all these generations. It’s nearly 700 years old.
“I think I shall die before that moment comes probably – but the fact that we still have some farms going back to 1337 is, I think, of enormous importance, that we have this connection with all of you.”
He joked: “Thank you ladies and gentlemen for paying your rent every now and then!”
● Prince Charles: Inside The Duchy Of Cornwall, Thursday, ITV, 9pm.