BBC newsreader Sophie Raworth had to take over the One O'Clock News bulletin mid-way through after its presenter Anna Ford pulled out with a sore throat.
Anna Ford's voice broke twice
Veteran newsreader Ford was replaced 18 minutes into the programme by the Six O'Clock News presenter.
"I'm afraid my voice is really giving up today," Ford told viewers as she handed over to her fellow newsreader.
Raworth, who was given just a few minutes' notice that she would be replacing Ford, told viewers she had "come to the rescue" before continuing with the news.
One O'Clock News editor Chris Rybczynski took the decision to take Ford off air after her voice faltered twice.
"Anna had flu all last week but she was fine for the summaries in the morning," said a BBC spokesman.
Sophie Raworth was given just a few minutes' notice
"But then her voice started to give way and the decision was taken to take her off air."
Raworth was already in the studio, preparing for the Six O'Clock News, when she got the call to take over.
"I was watching the bulletin and could hear that Anna was struggling," she said.
"Her voice went once, then twice."
Raworth was rushed in to take over the bulletin without any preparation and with no make-up.
"It was all a bit of a shock," she said.
A replacement presenter is always on hand to take over in such a situation, but a BBC spokesman said there was no record of it happening before.
"There is always another presenter around so that somebody can be called on at short notice," she said.
Viewers are more used to seeing Raworth presenting the BBC's Six O'Clock News, which she joined in January last year after leaving Breakfast News.
She had spent five years co-presenting Breakfast with Jeremy Bowen.
Anna Ford became the presenter of the BBC's One O'Clock News when it re-launched in May 1999.
Ford's BBC career began in 1976 for Man Alive; in 1977 she joined Tomorrow's World and from 1986 until 1988 she worked on Network.