Almost two in five of those polled said they used the networks to voice an opinion on things they feel passionate about, although a number regret it later.

Of the 39 per cent who speak out, 44 per cent said they felt they were making a difference, either through encouraging people to blog or tweet about the issue, or through prompting actual change.

However, a quarter of those polled said they have regrets about things they posted on social networking sites, with 44 per cent saying in hindsight that their comments were inappropriate and 27 per cent believing they had upset someone.