King Charles has vowed to the Commonwealth to ‘continue to serve you, to the best of my ability’ as he continues his treatment for cancer.

In a video message recorded at Windsor Castle, the 75-year-old monarch thanked people for their ‘wonderfully kind and thoughtful good wishes’ over his cancer diagnosis.

The King said: “In recent weeks, I have been most deeply touched by your wonderfully kind and thoughtful good wishes for my health and, in return, can only continue to serve you, to the best of my ability, throughout the Commonwealth.”

He refers to the origins of the Commonwealth in the network of countries that once formed the British Empire, saying: “The 75th anniversary of the Commonwealth is a moment to reflect on the remarkable journey our unique family of free and independent nations has made since 1949.

“Last year, the Bahamas celebrated its 50th anniversary of Independence, as Grenada has this year, and Papua New Guinea will next year.

“Each of these milestones – and many others like them – represent the fulfilment of countless aspirations and the achievement of such remarkable potential.

“And the Commonwealth’s growth, with new members continuing to join our family of nations, demonstrates clearly that whilst we may not all have a shared history, we have common ambitions for a better future – working together to build resilience and respond to global challenges.”

King Charles, who followed in his late mother’s footsteps as head of the ‘family of nations’, was unable to attend this year’s celebration marking the 75th anniversary of the Commonwealth due to his diagnosis and ongoing treatment.

In a royal first he recorded an address that was played to the congregation, reflecting on the journey the Commonwealth has made since its inception in 1949.

In his absence the family was led by his wife the Queen, accompanied by the Prince of Wales, and an extended roster of royals including the Duke and Duchess of Edinburgh, the Princess Royal, the Duke and Duchess of Gloucester and the Duke of Kent.

The King’s video was filmed last month at Windsor Castle, one of the places where His Majesty has been recuperating.

In what many will interpret as a veiled reference to colonialism and slavery, the King referenced ‘inequalities and injustices’ of the past ‘which still resonate today’and urged member nations to continue to ‘find ways of healing’.

Referring to climate change, the loss of nature and the social and economic changes new technologies are bringing, he said: “Our diversity means that these challenges affect us all differently and that we experience their impacts in different ways.

“Their seriousness, however, is common to each one of us. All of this means that we must work together to understand each other’s perspectives, including the inequalities and injustices which still resonate to this day.

“We must find ways of healing, and to support each other to pursue solutions. I cannot say often enough that it is by coming together that we create the best chances to improve our world and the lives of people everywhere,” said King Charles.