North Yorkshire marketing specialist Jennifer Middleton takes us behind the scenes of a new two-part film about Prince Charles and the Duchy of Cornwall

JENNIFER Middleton turned 50 yesterday – and marked the milestone with a career highlight.

On Thursday, the first of a two-part documentary about Prince Charles and the Duchy of Cornwall will be broadcast in the primetime slot on ITV. Two years in the making, it was the mother-of-two's first venture into film making – and one she would love to repeat.

Jennifer runs a well-established PR and marketing business, Lemon Zest, specialising in the food and farming sectors, with clients including Booths supermarkets. Previously she had worked on the Prince's Countryside Fund.

But the documentary – Prince Charles: Inside the Duchy – gave her the opportunity to mark one of the Duke of Cornwall and heir to the throne's own milestones: 50 years at the helm of the Duchy of Cornwall.

It was a new experience for her, working in television, and a detour from her main career in PR.

At the age of 21, the Prince inherited responsibility for this historic estate.

First thing's first. It's nothing to do with biscuits! The Duchy Originals brand was licensed off ten years ago to Waitrose.

In fact, the Duchy dates back to 1337 when it was established by Edward III to provide independence to his son and heir, Prince Edward. Following this tradition, the revenue from this estate is used to fund the public, private and charitable activities of the Duke of Cornwall and his children – which today extends to William and Harry and their families. In time, Princes William and George will inherit the role.

The documentary, which will air at 9pm, is an informative and heart-warming look at the work of the Prince and the Duchy of Cornwall. That name is deceptive because the estate extends beyond Cornwall to cover land and properties in 23 counties across England and Wales, stretching over 130,000 acres and covering 160 miles of coastline. Its diverse reach takes in everything from hilltop farms in the south west to Dartmoor Prison and the Oval at Kennington in London. It is worth £1billion and generates a profit of £21million a year.

Jennifer, who lives in Cawood in North Yorkshire, travelled thousands of miles during the production of the series. As associate producer, her role was to find the people whose stories would reveal the day-to-day workings of the Duchy. It took her as far afield as the Isles of Scilly, where she met a family of farmers who had been working for the Duchy for seven generations. In the film, you will see them picking botanicals from their farm to make gin, part of their drive for diversification.

"Going to the Scilly Isles was pretty magical," says Jennifer, who hails from Minneapolis and displays a slight American drawl despite living in England since her 20s. "We had such a good time there because it is such a different place.

"Many of the people there have four jobs. We met a farmer there who was also an air-traffic controller at the airport."

The documentary was made by a small team: Jennifer and two colleagues – series producer/director Charlie Clay and assistant producer Jamie Love. They had fun too, says Jennifer, recounting the day the trio took a boat to St Agnes in the Scillies to meet the gin-making family. "There are no cars on the island so they picked us up in a tractor and we had to ride in the trailer at the back, which was quite hilarious."

Another memorable filming day took place on a freezing Dartmoor in January. "We joined the Royal Marine trainees and I had to wear my Kate Adie jacket – flak jacket – and a helmet because they were using live ammunition," recalls Jennifer, who added she was touched by how well the trainees were looked after during the manoeuvres.

Another moving moment came during an interview with sheep farmer Sam Stables who disclosed how the Duchy had supported him while he suffered from mental health problems.

"If talking about his struggles resonates with just one farmer then that would be a great accomplishment for the documentary," says Jennifer.

Sustainability is a buzz word these days as concern over climate change has magnified into a global movement for action.

Caring for the environment – in both the natural and man-made world – has been a life-long passion for Prince Charles and one he has exercised in his management of the Duchy. Where once he was dismissed as eccentric and interfering for his outspoken views, particularly on architecture, today he is likely to be considered as a man ahead of his time as societies grapple with the impact of the climate emergency.

Jennifer acknowledges that the film may well change public perceptions about the Prince, but adds that was not the goal of the documentary.

"It's not just about him," she begins. "It's about the people in the Duchy who operate the estate inspired by the Prince of Wales. It's a community of people who want to run this sustainably."

The films, says Jennifer, reveal the Duchy as a huge "family" with the Prince visiting tenants regularly and amicably, recognising different generations of loyal tenants.

"The sense of community within the Duchy was palpable and really touching – and absolutely genuine," she says.

Jennifer's expertise in PR and her previous experience of working with Prince Charles and understanding Royal protocols made her a perfect fit for the commission. So what is His Royal Highness like in real life? "He is a principled gentleman," she says. "He is very comfortable in the Duchy."

Certainly, viewers will see a man at ease as he attends board meetings and branches out to visit staff and tenants across the vast estate.

Jennifer adds: "I hope they see it as a love letter to the British countryside."

Prince Charles: Inside the Duchy begins on ITV at 9pm on Thursday