The number of tweets posted by journalists from UK media outlets fell by almost 25%, according to the latest NewsTweet Index from PR firm Portland, with big falls at Sky News, which could be linked to its controversial social media guidelines introduced earlier this year.

Overall apparent changes in the tweeting habits of some of the UK’s top journalists saw 80,000 fewer tweets sent in the last three months compared to the previous quarter despite the ongoing economic turmoil, elections, big tax (and pastie) stories, the government’s problems and the on going Leveson inquiry, which all featured heavily.

That heavy dose of financial and business news was good for some though. The FT saw nearly three times the number of tweets as banking featured as the next most popular topic.

The fall in retweets led to some journalists falling down the ranking including Guardian editor Alan Rusbridger who dropped from 17 to 26. Overall, the Guardian sent more than 35,000 fewer tweets in the last quarter.

This has resulted in the BBC becoming the most active media organisation on Twitter as it registered a more modest 8% cent drop and remains well represented with its top place jouranlist being The Daily Politics presenter Andrew Neil at four.

Although notably while Laura Kuenssberg remains in the list (at 34, down 15) with her 78,000 plus followers, which she walked away with when she swapped the BBC for ITV, her replacement at the Beeb, Norman Smith, is nowhere to be seen in the list.

There is no change in the top position although there were some new entries. Paul Waugh, the editor at PoliticsHome, retained his position as the most influential journalist on Twitter. Coming up behind him is the New Statesman’s Mehdi Hasan who entered the list at number two as his political coverage struck a chord with his followers, encouraging a level of re-tweets and mentions second only to Waugh.

The decline in Twitter activity while across the board was highest at Sky News, The Guardian and The Telegraph. They all showed a 40% fall in Twitter activity.  While the fall at Sky could be linked to the change in its social media guideliness that is not true for the Guardian or the Telegraph.

Sky introduced its new guidelines n February and they caused a significant stir after it told its journalists to send tweets outside their brief to their relevant colleagues covering the issue and banned them from re-tweeting external content.

This move wasn’t well received and saw notably departures including heavy news retweeter Neal Mann who recently joined the Wall Street Journal’s social media team.

The BBC also introduced social media guidelines on how its journalists should engage on Twitter. The BBC introduced rules prohibiting its journalists from breaking stories on Twitter without clearing them with the BBC news room.

Channel 4 News, which saw several of its journalists make the list including Faisal Islam at number six, was the only media outlet to significantly buck the trend with a 25% increase in tweets on the three months ending December 2011.

This is the first quarterly decline in the total number of tweets sent by journalists at UK broadcast and newspapers, ending a run of double digit growth.

A higher signal to noise ratio?

It’s an interesting development. Many would have expected to see Twitter volumes to increase as organisations expand their social activity, but anecdotally the fall seems to reflect a less frenetic approach by journalists using social media across the board. Maybe it also represents a higher signal to noise ratio, which can not be a bad thing.

The fall in media tweets does beg the question, however, is this a quarterly blip we are seeing or is it part of a longer trend?

Mark Flanagan, partner for digital Communications at Portland, says: “If the number of tweets from traditional outlets fails to rebound it will create space in the twittersphere for journalists with more freedom. The big players will have to decide what is most important to them, safeguarding their reputation or maintaining relevance.”

Despite the falls in tweeting numbers one thing remains crystal clear: news will continue to break first on Twitter be it the exit of Kenny Dalglish as Liverpool FC manager or the death of singer Donna Summer.

Alberto Nardelli, co-founder and chief executive of Tweetminster says: “Twitter has reinvigorated journalism, and will no doubt continue to do so. More and more stories will be broken on Twitter; the only question is who will break them.

Here’s the full list (click on image to expand).