The far-right Dutch politician Geert Wilders intends to travel to London next week after an immigration tribunal ruling overturned a ban on visiting Britain.
The Home Office said it was disappointed after the tribunal rejected its claim that his presence could "inflame community tensions and lead to inter-faith violence".
The Freedom party leader immediately announced his intention to meet Ukip's Lord Pearson of Rannoch to discuss a showing of his anti-Islamic film Fitna later this month in the House of Lords.
Judge CMG Ockelton, who chaired the tribunal, said that Wilders's opinions were expressed strongly and in a way that was bound to cause offence but that the right of freedom of expression was important in a democratic society.
"Substantial evidence of actual harm would be needed before it would be proper for a government to prevent the expression and discussion of matters that might form the opinions of legislators, policy makers and voters," he said.
The ruling said there had been no evidence of public order problems or damage to community relations as a result of a previous visit by Wilders to Britain.
"It was more important to allow free speech than to take restrictive action speculatively," said Ockelton.
The judgment goes further, saying that even if there were evidence that Wilders posed a threat to public order it would still not have been necessary to ban him because the police would have been able to ensure no disorder took place and remove him if there was trouble.
The decision to ban Wilders was taken under regulations introduced in 2006 which allow the exclusion of those who represent "a genuine, present and sufficiently serious threat affecting one of the fundamental interests of society".
Wilders, who faces trial in the Netherlands for discrimination and inciting hatred, was turned back at Heathrow in February when the then home secretary, Jacqui Smith, banned him from entering Britain. He had been coming for a screening in the Lords of his film which calls the Qur'an a "fascist book". Smith said his presence had the potential to "threaten community harmony and therefore public safety".
Wilders said the ruling was a victory for freedom of expression and claimed Smith's decision had been politically motivated.
The politician was represented in the case by a British Muslim barrister, Arfan Khan, and the costs of just under £10,000 were funded by the Birkenhead Society, which "encourages free speech" and marks British Empire Memorial Day.
The Home Office said it would decide whether to appeal in due course.