Two men climbed hundreds of feet above London to tell the prime minister, Gordon Brown, to trust the people and hold a national vote.

All three parties promised a vote on the constitution at the last election. But Mr Brown says a vote is not necessary because the Lisbon document differs significantly from the old constitution.

"It's a question of democracy. All we are asking for is a vote on whether to ratify this treaty or not. It seems Gordon Brown doesn't trust us enough to let us have a vote."