Who's really who in the UK Twitterati

Last week, Twitter was valued at $10bn. A bit steep, perhaps, but the price tag reflects its influence, not its profitability – which is why Facebook and Google, the world's biggest web firms, are reportedly vying to buy it. Writing about the microblogging site used to generate shouts of derision. "People are dying in Afghanistan," the commenters would cry, making good use of their caps locks. "I DON'T CARE what some celebrity ate for breakfast!!!" But that kind of complaint has largely dried up: most experienced tweeters avoid the topic of breakfast, and even non-tweeters now appreciate the newsworthiness of social networks.

Twitter, we might as well admit, has become a crucial tool in any newsroom. Yes, if a showbiz correspondent is struggling to find a story, he or she may fall back on Kim Kardashian's cupcakes. But Twitter isn't just about celebrities. It's also where breaking news arrives from the streets of Westminster, Tehran and Cairo. (Or, indeed, Afghanistan.) It allows expert voices to conduct conversations in public – to share information, start campaigns, tell jokes and spread interesting or useful so-called content.

The site also starts instant trends, its users frequently massing around a given subject like a flock of migratory birds – and many such trends are started by a single influential tweeter. The Twitter 100 are the most powerful of those tweeters in the UK. This list , the first of its kind, was compiled by i in collaboration with PeerIndex, a social media monitoring group, which analyses and ranks people's online impact. Our methodology is described below. Essentially, we studied the size of each tweeter's audience and the frequency of their tweeting, but also looked at how engaged they were with that audience, and how much impact each tweet had – before seeking further input from a panel of experts in social networking media.

Inevitably, there are familiar names on the list , such as @SarahBrownUK and @Lord_Sugar; @StephenFry, despite his periodic absences, comes in at number 4. But there are also more obscure names (eg, Umair Haque at number 5), with fewer fans but a greater capacity to change minds and agendas with their tweets. The imperfect statistical method behind our rankings would be unlikely to satisfy @BenGoldacre, scourge of bad science (no 18). But without a spot of judicious curating, we'd be unable to reflect the glorious range of voices on Twitter. Several of them could doubtless tell you whether Twitter is really worth $10bn to Google. To the rest of us, it's priceless.

Read the list here