Politicians may rue the influence of events on their carefully planned schedules but for TV advertisers they can be gold dust.

Gold dust in the sense that events bring in bigger audiences, particularly hard-to-reach viewing groups, as well as re-enforcing the consensus that TV is the biggest game in town.

In the US, the pinnacle of event TV – appointment-to-view TV that people want to watch live – is the Superbowl. Recent years have seen its expensive advertising airtime increase rather than diminish. By mid-November 2007, with months to go before the main event on February 3rd, more than 90 per cent of spots had already been sold despite the £1.3 million price tag.

One reason for the strong advertiser interest is that events attract bigger audiences making them attractive to marketers who want to reach a mass audience.

Analysis by MediaCom of viewing levels for UK TV events – defined as sporting coverage, calendar or programming events – found that viewing was significantly up.

For Big Brother eviction nights viewership of 16-34-year-old adults was nearly double that recorded during the rest of the broadcasters' peak schedule that night.

In fact Channel 4's entire evening benefited with peak viewing markedly ahead of Friday night ratings before Big Brother started.

And the same pattern was also seen on X-Factor, where viewing in Saturday peak in ITV 1 was static before the series started. Ratings were dramatically increased once the show started its run but then dropped back to normal levels after the finale.

Rhys McLachlan, head of broadcast implementation at MediaCom, says event TV is particularly powerful for brands that want to launch to reach a wide cross section of the population.

"Event TV is consistently better than any other media in helping us to deliver fame," he says.

And even within events such as sporting tournaments, some elements of an event will attract a broader audience.

"Rugby World Cup final audiences were considerably broader than any of the rugby that had gone before and Brazilian Grand Prix audiences were broader than any of the Formula 1 that had gone before," he says. "The only thing with sport that we are unable to control is there's a huge amount of out of home viewing."

He argues that when events are televised consumers tend to revert to older, more static media consumption patterns, basing an evening of viewing around the main event thus explaining the benefit to the rest of the schedule.

"People watching at 19.00 tend to stay watching the whole evening," he says. "There's a halo effect generated that's truly important in this day and age when the demands on our attention are becoming ever more."

ITV's integrated planning director Simon Orpin agrees: "These events will still attract huge audiences of people that will sit down and make a whole evening around it," he says.

McLachlan also argues that such events have a resonance well beyond the television. Recent events such as the Rugby World Cup final and the end of the F1 season combine with coverage on TV to provide the "unifying force of the social fabric of the nation". "They are the conversational currency that many brands want to be part of," he says.

"If I'm Nokia sponsoring X Factor I can truly generate some cross media touch points," he says, reaching both the broader consumer base as well as the core consumer with further, more specific media partnerships.

It's this wider resonance that also benefits other media owners as well as other businesses in the community. "The publican community should be grateful to TV for filling up their seats and emptying barrels of beer on a Tuesday night for Champions League matches at the beginning of November. These are nights that would otherwise be dead," he says.

The idea that event TV also brings a boost to surrounding activity is also supported by ITV, which points out the increase in traffic to its website during the Rugby World Cup or the number of viewings for Susan Boyle videos on YouTube since she appeared on Britain's Got Talent.

For Alex Sullivan, partner at Fallon London, the key benefit of advertising around a TV event, is the ability to hit hard-to-reach audiences repeatedly.

"It's hard to get high audiences repeatedly in the same place. That's why sponsorships of things like X Factor and Big Brother are so valuable," he says.

The other type of event is that created by the calendar. Although the sponsorship is not running in 2007, Rennie was a long-time sponsor of the ITV 1's Christmas programming, firstly through MediaCom and more recently via PHD.

Ivan Lazarov, account manager at PHD's specialist unit Drum, points out that the brand had rivals who were spending more right through the year.

Sponsoring the Christmas package was right "in terms of when they needed to have their biggest advertising presence and also in terms of sales".

Christmas viewing offered a big TV occasion, as well as a family presence which, combined with humorous idents, enabled the brand to connect with a period of traditional excess.

"It was a great time for the family to get together for all that shared viewership," he says. "The package was really good in terms of return on investment, really high exposure and the idents were really memorable for people. There were lots of plus points."

And, he says, it represented great media value, delivering close to a thousand 30-second equivalents and nearly 80 per cent cover at 25 OTS via an association with nearly 100 different programmes over three weeks.

ITV's Orpin says that brands have taken all manner of approaches to planning for televisual feasts. Some will plan in detail months ahead of the booking deadline, while others decide to run broader campaigns that are up-weighted in specific programming. Finally there are the tactical brands that "come in quite late".

"For the Rugby World Cup some brands will plan to have a spot in every game and they'll plan that in February," he says. "Other people will make sure they have campaigns running across the period but may make sure they have an up-weight around those events if their target audiences are relevant."

Orpin argues that for sporting events the appeal stretches beyond the local teams. "For both the Football World Cup and Rugby World Cup we were still getting fantastic audiences even for games that do not feature any of the home nations. The world cup just captures everyone's excitement and they want to watch a game."

Part of the consumer appeal of these shows is the fact that advertisers invest heavily in their content too.

"It's a fantastic opportunity for advertisers to showcase their products to a really engaged audience," he says. "With something like the Rugby World Cup or Football World Cup we tend to get a break environment that is really quite striking. It's a place for people to really line out fantastic creative linked to the theme of the content."

The attractiveness of the live events for both broadcasters and advertisers is such that ITV is moving previously pre-recorded events such as the Brits into the live arena

"Choice is huge in terms of what TV consumers want to watch, when they want to watch it and where they want to watch it. That's the unique selling point of big events," he says.

Perhaps the final message for advertisers considering an event-based strategy comes from MediaCom's McLachlan who argues that it doesn't even have to be a World Cup final or grand prix decider to attract a large audience.

The most recent Manchester United versus Arsenal game was "one of the biggest global broadcast events ever". "More than one billion people watched that globally," he points out. "The UK has a capacity to generate event TV not just on a scale but on an international scale as well."