The Archbishop of Canterbury says his memory is only as good as his dog's after a documentary revealed he had fluffed the prayers during a rehearsal for the King's Coronation.

Most Rev Justin Welby was speaking after a preview of the BBC programme showed him reading out the prayers to King Charles before stopping and looking at notes while admitting: “This can’t be right.”

He was reciting "In the blessing of God Almighty, the Father, the Son and the Holy Spirit, be amongst you and remain with you now and...…" when he stopped and said : "that can't be right." The Archbishop of York's voice can be heard in the background, saying : "You must have said this before..." The King can then be seen shaking his head with laughter.

Archbishop Welby then continued with the correct wording: " Be with you and remain with you, always, Amen."

In the programme, Charles III: The Coronation Year, he admitted it had been a "glitch" but that the King had given him a "nice smile". And he joked: "I have a memory that is probably about as good as our spaniel's — in other words, zero."

The documentary will be broadcast on Boxing Day.