Prince Charles became Prince of Wales aged just nine years old but it was not until eleven years later, in the summer of 1969, that he was formally invested with the title by The Queen in a spectacular ceremony at Caernarfon Castle. The event was watched by half a billion people around the world, putting Wales firmly on the global stage. But it was not without controversy as, for some, the celebration also became a moment for nationalist protest. Five decades on, The Prince is now the longest serving Prince of Wales in history and his affection for the nation and its people is as strong as ever. To commemorate an extraordinary half century of service to Wales, ITV has been granted unique access to The Prince at his secluded Welsh home of 'Llwynywermod', deep in the Carmarthenshire countryside. In a very personal interview, The Prince reflects on the turbulent events surrounding his investiture and how, as a young man, he fell in love with the magic of the Welsh countryside. During the film, The Prince and his wife, The Duchess of Cornwall, are filmed on their annual Welsh tour, making new friends and reconnecting with people from The Prince's past.