Geert Wilders had been invited to Westminster to show his 17-minute film Fitna, which criticises the Koran as a "fascist book", by a member of the House of Lords.
But on Tuesday Jacqui Smith, the Home Secretary refused Mr Wilders entry because his opinions "would threaten community security and therefore public security" in the UK.
Mr Wilders went ahead with his trip anyway, and flew from Amsterdam to London on a British Midland flight.
When he arrived at Heathrow airport he was met by two plain clothed officers from the UK Border Agency.
As he was being led away, Mr Wilders said: "I am not nervous but is this how Great Britain welcomes a democrat?"
“Banning Geert Wilders from the UK is not the solution. Just as the ideas of non-violent Islamist groups like Hizb ut-Tahrir should be tackled through debate and argument, so should those of Wilders and others. Freedom of speech should be protected – so long as people do not use this freedom to call for violence against others.
“Wilders has evidently been convinced by the words and actions of Islamists and jihadists that Islam is inherently violent and intolerant. We therefore challenge him to an open debate in which we will argue that Islam is not an inherently violent religion and that, contrary to what he apparently believes, Muslims are not a threat to Europe and its values.”
Ed Husain, the co-Director of the Quilliam Foundation, says:
“Geert Wilders is undoubtedly an ill-informed, hate-driven bigot with many unpleasant views but he is not directly inciting violence. As a result, unlike in the case of Yusuf al-Qaradawi, I do not support the decision to ban him from the UK. By threatening parliament with a mob, Lord Ahmed is contributing to the negative portrayal of Muslims and their religion.”
But a free society cannot be structured to soothe the hardcore faithful. It is based on a deal. You have an absolute right to voice your beliefs – but the price is that I too have a right to respond as I wish. Neither of us can set aside the rules and demand to be protected from offence.Yet this idea – at the heart of the Universal Declaration – is being lost. To the right, it thwacks into apologists for religious censorship; to the left, it dissolves in multiculturalism. The hijacking of the UN Special Rapporteur by religious fanatics should jolt us into rescuing the simple, battered idea disintegrating in the middle: the equal, indivisible human right to speak freely.