Twitterers in Coventry have the highest average number of followers with 549 per person compared to 256 in London, according to a survey by the Social Media Library.

It comes a week after PRWeek generated controversy by revealing which PR agencies were most active on Twitter and which PROs had most followers.

Social Media Library chief executive Graham Lee said: 'Having a large number of followers can have quite a powerful effect. A Twitter post will appear immediately in all follower's news feeds and desktops.'

But other PROs were scornful of such measurements. Citigate Dewe Rogerson director Phil Szomszor said: ‘There seems to be a general obsession among many PROs for who comes out top and who's got the most followers.'

Paver Smith MD Dougal Paver said quality was more important than quantity: ‘Clearly the person who has twittered once and gained new business or coverage for a client is more effective than someone who twitters a hundred times a day and achieves nothing.'

Meanwhile, the founder of Twitter told PRWeek that the medium is an invaluable tool for the PR industry. Biz Stone said: ‘The pace of business is getting closer to real-time and it's important to have communication tools that help you operate at this pace. Twitter helps people share information quicker and more efficiently.'

The website does not currently have PR support but relies on social media to promote itself. ‘We make use of Twitter and our company blog to share information. The blog is good for getting into details and our Twitter accounts are a great way to spread the information quickly,' said Stone.

Click here for the complete Social Media Library Twitter stats