The NewsTweet Index is published by Portland in partnership with Twitter analysts at Tweetminster. By studying the content, impact and quantity of tweets generated by UK journalists on Twtter, the NewsTweet Index illuminates the trends and personalities which are shaping Britain’s media Twittersphere. The Index includes:

• The Top 50 Media Tweeters
• Which Publication is dominating Twitter
• Which stories have been most heavily covered in the media

Source of data Portland

For an interactive list – see this pdf file