Ian Burrell: Twitter is open for business, and that means ads coming to a tweet near you

Viewpoint: Engagement scores at Twitter are said to be at 3-5 per cent, an extraordinarily high figure

Except for the nameplate on the meeting room door that reads "@barnowl", there is little to indicate that Bruce Daisley is sitting in one of the hubs of a global media enterprise that is expected to generate revenues north of £160m this year. The fourth-floor London headquarters of Twitter, in the media district sometimes called Fitzrovia, is less prestigious than that of other Internet giants such as Microsoft and Google, with their breakfast bars and games rooms. Yes, there are the fruit bowls and supplies of mineral water – pre-requisites of any new media workplace – but Daisley acknowledges that "we are a pretty small team here".

That's about to change though, as Twitter spreads its wings in response to the growing success of its advertising-based model, which was introduced two years ago in the United States and arrived in Britain last September.

Daisley, who arrived at the start of the year from Google, says his "biggest challenge" is letting people know that Twitter is open for business. "We are recruiting, we are trying to build the team here and trying to get the message of how well this is going out to as wide an audience as possible." Twitter UK will be hiring more sales staff, more engineers and more marketing people.

Dual screening – watching television, while simultaneously discussing the programmes on social media – has become a national habit. Brand managers want to be part of that conversation on Twitter. Daisley says that engagement scores at Twitter (the frequency with which a user responds to a commercial message) are at 3-5 per cent, an extraordinarily high figure. Twitter users might engage by "retweeting" commercial messages to their followers, by endorsing the tweet as a "favourite" or by simply clicking on a tweeted link. He says there is a high value to a commercial client in being placed amid the tweets of a user's most trusted sources and treasured subjects. "It's the power of sitting adjacent to people's passions and interests."

The options for business range from the Promoted Trend, which is sold daily and highlights the subject as a hot topic of the day, to a Promoted Tweet, which ensures the message appears in the timeline of users whose Twitter activity has suggested that they might be amenable. A Promoted Account means the brand is advertised as one that users might wish to follow. All promotions are marked with an orange arrow.

Daisley says that Twitter monitors each ad closely to see if it's working. "We can tell pretty quickly if no one is clicking on an ad," he says. "We have already got a strong track record of knowing what success looks like." Case studies are used to advise clients on what works. Cadbury's "Retweet for Sweets" campaign to promote its chocolate bar Wispa Gold enjoyed a 25 per cent engagement rate. The British Heart Foundation used Promoted Tweets to drive 1.7 million views of its life-saving CPR video featuring Vinnie Jones.

As Daisley sits in @barnowl (other rooms in the office are called @robin and @osprey), he is aware that if Twitter overdoes the advertising then users may come to see the platform less as a chirruping feathered friend and more as a Hitchcockian nightmare. "Defending the users' voice is really important," he says. Twitter is only six years old and, until six months ago, users in Britain had become accustomed to inter-acting in an environment free of paid-for advertising.

But so far there have been no British "Twitter storms" over inappropriate advertising. That's why Daisley is convinced that the long-asked question as to how this Internet phenomenon would make money has now been answered. "Twitter's business model is advertising," he says. "You struggle to see evidence of why anyone would think otherwise now."

i.burrell@independent.co.uk