The Archbishop of Canterbury has been forced to cancel his annual Christmas Day sermon after coming down with a heavy cold.

The head of the Church of England - who the Dean of Canterbury will fill in for - was due to say Christmas should not be reduced to "utterly remote and fictional" stories about "swapping photos, shaking hands and sharing chocolate".

Giving his Christmas Day sermon at Canterbury Cathedral, the Archbishop had planned to remind worshippers that the famous First World War truce between German and British troops quickly gave way to more killing.

"At Christmas 1914, soldiers took the risk, crossed a battleline and kindled an evening of friendship and football," he was expected to say.

"It is the moment all have picked on this year, whether in adverts or sermons.

"The truce illustrates something of the heart of Christmas, whereby God sends his Son, that vulnerable sign of peace, to a weary war-torn world.

"The problem is that the way it is told now it seems to end with a 'happy ever after'.

"Of course we like Christmas stories with happy endings: singing carols, swapping photos, shaking hands, sharing chocolate, but the following day the war continued with the same severity.

"Nothing had changed; it was a one-day wonder. That is not the world in which we live, truces are rare."

He was expected to urge worshippers not to reduce the story of Christmas to something "utterly remote, about lives entirely different, fictional, naive, tidy".

"Jesus came to the reality of this world to transform that reality - not to take us into some fantasy kind of 'happy ever after' but to 'Good News of great joy for all people'," the Archbishop is due to say.

Meanwhile, Pope Francis called for "tenderness" and "warmth" in his Christmas Eve mass.

"Do we have the courage to welcome with tenderness the difficulties and problems of those who are near to us?" the pontiff asked in Saint Peter's Basilica, filled with some 5,000 worshippers.

"Or do we prefer impersonal solutions, perhaps effective but devoid of the warmth of the Gospel? How much the world needs tenderness today."