There are, it seems, some gigs so big that even royalty can't land them. Yesterday afternoon, in an honour not even afforded the Queen's Speech, all five terrestrial TV channels and more than 20 cable and satellite stations simultaneously broadcast the new Band Aid 20 charity single.

Millions of viewers tuned in at 5.55pm to see the video, which mixes footage of the famine in Africa with images of pop stars weeping as they struggle to comprehend the enormity of the situation.

"It is something completely unprecedented," said a Band Aid spokeswoman. "I have never known even a royal occasion to be shown on all channels like that.

"What we have got to make sure is that as many people as possible buy the single and I can't think of a better way of doing that."

The video was introduced by Madonna, who performed at the original Band Aid concert but did not take part in the recording of the new song.

Over images of starving children, she said: "Once again, here we are 20 years later. More people die of hunger in Africa than war and Aids put together. In a world of plenty, it is hard to imagine that most African children will go to bed tonight hungry. Bob Geldof and his friends are here to remind you that we can never forget. Not ever. Feed the world."

The single, an update of 1984's Do They Know It's Christmas?, features a host of stars including Coldplay's Chris Martin, Dido and Robbie Williams, who sing the opening lines of the song.

U2's frontman, Bono, reprises his famous, "and tonight thank God it's them instead of you" line. Among the other singers who contributed are the Sugababes, Fran Healy from Travis, Justin Hawkins from The Darkness, Will Young, Jamelia, Ms Dynamite and Joss Stone.

The video also shows the musicians who didn't sing, including Sir Paul McCartney playing bass, Radiohead's Thom Yorke on piano and Danny Goffey of Supergrass on drums. Blur's Damon Albarn is seen serving tea to the singers.

But Robin Eggar, a journalist who was at both the 1984 and 2004 recordings, said time had numbed the potency of the original.

"People are so used to seeing images of hunger and famine on their screens," he said.

"When we turn on the TV to see Iraq or Darfur every day, the footage used in the video can't be as dramatic.

"But I don't think anyone could expect this video to have the same impact as the first. In 1984 it was a spontaneous event, this time it is more of a media creation."

The new single will be in the shops on November 29 and has long been tipped as the Christmas number one.

It is available to download and will be launched as a charity ringtone on Monday.