The Monarch has taped a intimate address concerning his battle with cancer, scheduled for transmission as part of this year's fundraising drive, organised by medical research organisations and Channel 4.
Official sources stated the King would talk about his "recovery journey" as a person living with the disease, in a video message on Friday at the evening slot.
The recording, recorded at Clarence House two weeks ago, will highlight the critical nature of cancer screening checks to ensure more people detect the condition at an initial point.
This constitutes a uncommon insight on the medical condition of the King, who has been in a course of therapy since his condition was announced in early last year. However, it is believed improbable the King will disclose his particular diagnosis.
The awareness event each year generates donations for medical research and patient care and encourages people to get health assessments to boost the odds of an early diagnosis.
The King's public discussion about his health challenge, and living with cancer, has been intended to increase understanding and to persuade more people to get checked - and this will be advanced with this unique royal involvement.
Up until now the King's key philosophy to his cancer has been to keep working, preserving a full diary alongside his regular rounds of therapy, and he is understood not to have desired to be defined by his illness.
Recently has seen the Sovereign, undertaking several international tours, notably to Italy and Canada, and welcoming the biggest number of official guests to the UK for a generation, which included the German president recently.
The upcoming charity programme on the network, featuring presenters like Davina McCall, Adam Hills and Clare Balding, will urge people not to be scared of getting preventative tests.
Each presenter have been affected by cancer - one host disclosed in November she had had an operation for a tumour, while Clare Balding was diagnosed with the illness more than 15 years ago. Comedian Adam Hills has previously spoken about his parent, who had stomach cancer and then later blood cancer.
The programme will target the estimated 9m people in the UK who health organisations estimate are not current with NHS screening schemes, with an digital tool to let people see if they are qualified for tests for several common cancers.
In an attempt to demystify cancer checks and illustrate the benefit of early diagnosis there will be a live broadcast from treatment centres at Addenbrooke's and Royal Papworth hospitals in Cambridge.
"The goal is to take the fear surrounding cancer screening and prove the public that they are not alone in this," stated one of the hosts.
Currently in the UK, there are several key publicly available checks - for major health concerns - available to eligible individuals.
A new preventative initiative is also being gradually implemented for anyone at potential risk of contracting the disease, primarily aimed at people in a specific age bracket, who have a smoking history or were former smokers.
Male patients may enquire about prostate screenings, but there is not a universal scheme operational.
The charity campaign, which has collected £113m since 2012, is financing multiple medical projects encompassing thousands of patients.
The Monarch, in a message for dignitaries at a event for cancer charities in earlier this year, had referred to recognising the "overwhelming and at times scary situation" for cancer sufferers and their loved ones.
But he noted his experience of managing cancer had revealed that "periods of great challenge of illness can be illuminated by the kindness of others," as he praised those who looked after those receiving treatment.
The Palace has not revealed the nature of cancer the King has, or the medical care he has been given. The King's cancer was discovered after he had had a prostate procedure.
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