The TweetLevel index, launched by PR agency Edelman, uses an algorithm incorporating elements such as the number of followers, the number of retweets, and the level of engagement and influence of a Twitter user to calculate how influential they are compared with the rest of the Twittersphere.
Using Edelman's metric, the most influential tweeter in the world is the bitchy Hollywood gossip blogger Perez Hilton, with a score of 87. He ranks as not only being more influential than Mashable, which has a score of 86.3, but the ranking also finds that more people think Perez Hilton is trustworthy than Mashable.
Stephen Fry, who has nearly one million followers, is only at number 18 on the list with a score of 80.4 on the influence scale. Brand Republic's twitterfeed only has a trust level of 59.5, so clearly it can't work all that well.
Robert Phillips, CEO of Edelman in the UK, said: "This may seem like a bit of fun but there is a really serious side to it.
"Too often people think that mere popularity is important but influence and ultimately engagement are what matters."