The 74-year-old writer, director and actor formed the iconic comedy group alongside Palin, John Cleese, Terry Gilliam, Eric Idle, and Graham Chapman.

He was recently told by doctors he has primary progressive aphasia - a type of dementia affecting the brain's frontal lobe.

Terry's diagnosis was revealed when it was announced he would be honoured with a lifetime achievement gong at the British Academy of Film and Television Arts (BAFTA) Cymru (Wales) Awards.

"Terry has been diagnosed with primary progressive aphasia, a variant of frontotemporal dementia," his spokesman said on Friday (23Sep16). "This illness affects his ability to communicate and he is no longer able to give interviews. Terry is proud and honoured to be recognised in this way and is looking forward to the celebrations."

Michael Palin took to Facebook on Saturday (24Sep16) to describe watching his friend battling the disease as "painful".

"Terry J has been my close friend and workmate for over fifty years. The progress of his dementia has been painful to watch and the news announced yesterday (Friday) that he has a type of aphasia which is gradually depriving him of the ability to speak is about the cruellest thing that could befall someone to whom words, ideas, arguments, jokes and stories were once the stuff of life," Palin wrote.

"Not that Terry is out of circulation. He spends time with his family and only two days ago I met up with him for one of our regular meals at his local pub. Terry doesn't say very much but he smiles, laughs, recognises and responds, and I'm always pleased to see him. Long may that last," he concluded the emotional post.

BAFTA Cymru organisers are hoping Jones, who directed Monty Python's Life of Brian and Monty Python's The Meaning of Life, and co-directed Monty Python and the Holy Grail with Terry Gilliam, will still attend the awards on 2 October (16).

It is thought he will be accompanied by a family representative and won't give a speech.

Hannah Raybould, Director of BAFTA Cymru, announced the accolade was to celebrate the Welsh-born comic's career achievements since the 1960s.