Activists climbed the structure shortly after 2am before unravelling banners proclaiming "Referendum Now" and "Give Us Our Vote".
It comes two days before MPs are set to vote on a Conservative amendment to the EU Treaty Bill, calling for a referendum on the issue.
On Sunday, campaigners had claimed they have overwhelming public support for a referendum. The 'I Want a Referendum Campaign' released the results of its own referendum across 10 marginal Labour and Lib Dem constituencies showing 88% backing for putting the treaty to a vote of the public.
The Government dismissed the exercise as a "gimmick", saying that most supporters of the treaty had simply ignored the referendum.
But campaigners said that it sent a "clear message" to MPs that the public wanted to have their say on the treaty.
The 'I Want a Referendum Campaign' said that it sent out 420,791 ballot papers based on the latest publicly available electoral roll. At total of 152,520 - 36% - were returned, of which 133,251 were in favour of a referendum.
The constituencies covered included those of Europe Minister Jim Murphy (East Renfrewshire), Home Secretary Jacqui Smith (Redditch), Transport Secretary Ruth Kelly (Bolton West), and Lib Dem home affairs spokesman Chris Huhne (Eastleigh).
Campaign chairman Derek Scott - a former economic adviser to Tony Blair - said that it was a "magnificent turnout" and a "great result". He said that Labour and the Lib Dems should now honour their election manifesto promises to hold a referendum on the EU constitution, which, the campaigners say, is broadly the same as the new treaty.
The Government, however, argues that a referendum is not necessary as, it says, the treaty is substantially different from the now abandoned EU constitution.
Story from AOL UK.
Ah, but it is not! It is virtually the same document.
More propaganda from the English government.
Come on people, stand up & fight their lies & demand that they speak the truth.
England is already the most surveillanced country in the world &
the peoples rights are being shat upon, get up & fight for your vote.