THE 50th anniversary of the investiture of Prince Charles as Prince of Wales at Caernarfon Castle will be marked with a revealing S4C documentary that tells the story through the eyes of protest singer and language campaigner Dafydd Iwan.

In the programme Dafydd Iwan: Y Prins a Fi (Dafydd Iwan: The Prince and Me), one of the central figures in the national movement over six decades embarks on a personal journey to shed new light on one of the most controversial events in Wales during the 20th century.

As well as hearing people's recollections of the day, the programme features remarkable historical archive material which will take us back to a turbulent period in the living memory of many S4C viewers.

The year 1969 is remembered as a year of protest, hope and paranoia in Wales with Plaid Cymru and the Welsh Language Society gathering momentum.

Into this mix came the investiture, an event that divided opinion, creating tensions within organisations, communities and families.

With some 500 million watching the colourful ceremony on television, the eyes of the world were on Wales and Caernarfon; the pomp and pageantry was enjoyed by most people in Wales, the UK and the world, but caused resentment, anger and resistance among some Welsh nationalists.

“The response to the protests against the investiture was the greatest hatred I’ve experienced in politics," said Dafydd Iwan, who was a young 25-year-old campaigner at the time of the investiture. "Terrible things were said, and my life was literally threatened, both in print and verbally,”

“Unfortunately, Charles was portrayed as a symbol of purity and perfection and I as the devil incarnate and public enemy number one,” says Dafydd, a son of a minister who spent much of his formative years in Llanuwchllyn, near Bala, Gwynedd.

At the time of the investiture, Dafydd Iwan was Chairman of the Welsh Language Society. Ironically, at first, he was eager to avoid giving the investiture too much attention and considered the campaigns to secure language equality in public life, including Welsh language road signs, education and broadcasting far more important.

As one of the heroes of the language movement, Dafydd was inevitably drawn in to the investiture debate.

His views about the event were expressed eloquently in satirical protest songs such as ‘Carlo’ and ‘Croeso Chwedeg-Nain’.

“What we have to remember is that it was a time of a great awakening among young people in Wales and of re-defining our relationship as Welsh people with the UK and with England.

"The investiture was a great opportunity to say. ‘Right, we’re not just going to lie down and accept the status quo. This is an opportunity to say that we don’t accept the so-called Prince of Wales forced upon us after the [Norman] conquest. We’re going to make our own mark.”

Dafydd Iwan insists that the investiture inspired a generation of Welsh people to campaign for the civil, language and political rights that Wales now enjoys.

In the thought-provoking documentary, Dafydd will compare the conflict and difference of opinion we are witnessing today as the result of Brexit to the discord and disunity present in Wales in 1969. He will also ask whether the role of the Monarchy in Wales continues to divide opinion here.

The recent controversy over renaming the Severn Bridge ‘The Prince of Wales Bridge’ suggests it is still a hot topic. And Dafydd Iwan, while respecting Prince Charles’ views on many issues such as conservation and the ecological future of the planet, has not changed his mind on the monarchy.

“I regret nothing about the investiture campaign, but we need to show people that you can oppose something fiercely but do so without hatred.

"The investiture is part of our history, and whether we are for or against, we must live with this part of our history, but we need to learn not to make the same mistakes again. We need to move on, that’s the important thing.”

Dafydd Iwan: Y Prins a Fi, Sunday July 7 at 8pm on S4C also on demand: s4c.cymru/clic, BBC iPlayer

English subtitles are available.