Once upon a time they were a common feature during soap operas in the 1950s.

But now Channel 4 has invoked the spirit of a bygone age with a live TV advert.

In a bid to try to stop the trend of viewers switching over when adverts come on the broadcaster planned an eye-catching advertising stunt.

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The team of skydivers, jumping despite heavy cloud cover - forms the letter H

At 8.10pm on Thursday, during an advertising break for dinner party show Come Dine With Me, 19 skydivers, each with cameras took centre stage.

They had only three minutes and 20 seconds to spell out a message to viewers in a series of challenging formations over Madrid.

The £500,000 stunt, to promote Honda, featuring a team of international sky diving  champions, has been given the go-ahead by Spanish officials.

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Having split up, they rejoin to produce the letter O

But they had to keep an eye on the weather as forecasters were predicting rain when the action was due to take place.

Channel 4 has said no risks would be taken and that a rehearsal, filmed on Wednesday, would be used in its place if the live jump could not happen.

Broadcasters are increasingly likely to resort to attention grabbing tactics like this to get people to watch adverts.

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Hurtling through the clouds, they form the letter N

The spread of personal video recorders like Sky+ means many can now simply skip the adverts, to avoid being given the hard sell.

The advert, inspired by Honda's phrase "If it's difficult it's worth doing" heralds the company's new advertising campaign, which launches on June 1.

The idea was developed by Channel 4 who is desperately trying to up its advertising revenue.

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With the ground now becoming visible, they manage the letter D

Last year the broadcaster revealed its first operating loss since 1992, with a fall in the number of people watching adverts.

The team of expert sky divers included European champion Phil Curtis, four world champions and nine national sky diving champions.

The advert, lasting 3 minutes and 20 seconds, saw the skydivers racing against time to make sure the commercial message reached British TV viewers.

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Mission accomplished: Just in time before they have to pull their rip cords, the team forms the letter A

Andy Barnes, sales director, Channel 4, said: "This concept breaks the boundaries of the 'perceived' confines of TV advertising, which is something Channel 4 is striving to do."

The advertising market is already set for major changes in the coming months.

Regulators are expected to allow the introduction of some product placement in British TV shows.

On top of this Ofcom is looking at whether programmes could be allowed to be interrupted by scores more advertisements under a revamp of legislation.

It put forward proposals which could see an increase in the frequency and length of commercials on screen.

One option is allowing 30-minute shows programmes such as Coronation Street to double commercial breaks to two per episode or three for a 60-minute show.