Lesley Riddoch claims that US-based social network site has maimed Rupert Murdoch

She explains that if those ‘hostile’ to Murdoch’s takeover have succeeded, then they have undertaken “a high effective piece of international e-activism.”

Riddoch, who heads up her own media company called Feisty Ltd, claims that …”a new ethically motivated, global policeman is on the trail of the international wideboys which no individual government appears ready or willing to tackle. About time.

Riddoch highlights the roles played by Chris Bryant MP, Hugh Grant, broadcast union Bectu and The Guardian in damaging the ‘Murdoch empire’ but says it was none of those who ‘brought the might Murdoch empire to its knees’.

If the board members of Ofcom stand by their guns and declare News Corp cannot pass their "fit and proper" test and veto the proposed takeover of BSkyB, points out Riddoch, there can be only one conclusion: “It was not the great and the good wot won it - it was the social media.

Riddoch claims that social media site Avaaz inspired objections to be made within government and that ‘blind spots’ in regulations were identified by the site.

Riddoch says that Avaaz is a nine million-person global campaign network that "works to ensure the values of the world's people shape global decision-making".

She explains: “Members are spread across 13 countries and the website operates in 14 languages. It takes no money from government or corporations, is largely funded by public subscription and promises to ‘close the gap between the world we have and the world we want, one campaign at a time’.

Riddoch claims that Avaaz has recently won several targeted and last-minute international efforts. In April, a 73-year-old Indian woman, Anna Hazare, declared a fast unto death until the government passed a powerful new anti-corruption law. Four days later the public outcry forced India's government to give in.

In May, 1.5 million e-mail messages helped stop the Ugandan parliament from approving the death penalty for homosexuality.

Says Riddoch: “Avaaz focuses cleverly on campaigns with defined goals, limited timescales - and winability.

“That , of course, raises questions. Who are they? Can mass virtual campaigns stay clear of the spammers whose destructive efforts may yet hobble the internet as a powerful tool for democratic change? Above all, might they aid and abet the very politicians they hold to account?

“Avaaz has fast become expert at creating momentum during public crises and proving people power mobilised by social media can work in the short term. But after that?

“The uncomfortable truth is that without some blunders by the Murdoch empire itself, the Milly Dowler revelation and the nationwide wave of revulsion it provoked might never have been made public.”

Riddoch points out that it was News Corp bosses who warned there was "worse to come" when the story fully emerged last week, and James Murdoch thought he could prune the problem by axing the News of the World.

“All of these cack-handed attempts to control public opinion have simply swung it firmly behind News of the World staff whose Dunkirk-like stoicism has left them looking like heroes and News Corp bosses

“In the old days, the excesses of capitalism were checked by the trade union movement, government watchdogs and - you'd like to think - conscientious MPs.

“In the case of Murdoch's attempt to gain control of the world's media, these forces were all neutralised. MPs were threatened and cowed. Trade unions were inert - more worried about job losses among their members,”

Finally Riddoch summarises the role of social media, claiming that it has “become more effective watchdogs,” than those paid to perform such a task.

"Unless politicians act decisively to stop Rupert Murdoch in his tracks, we may wonder if they have become expendable, too,” concludes Riddoch.