Peter Tatchell scraps idea of making citizen's arrest on the Pope

They met over tea and biscuits in a fifth-floor boardroom at New Scotland Yard, overlooked by portraits of the Queen and the Queen Mother. On one side of the table was the Most Reverend Peter Smith, Archbishop of Southwark – one of the most senior Catholic clergymen in the country.

Opposite him were representatives of Protest the Pope, a coalition of human rights campaigners and secularists who will lead demonstrations against Pope Benedict XVI's state visit to Britain next week. Many of its leading members have previously said they want to the pontiff to be prosecuted for "crimes against humanity". But after taking legal advice, members of the group admitted there would be no attempt to arrest the Pope because he is protected as a head of state.

"The Pope has sovereign immunity from prosecution under British law; it wouldn't work," said Peter Tatchell, the human rights activist who has previously tried to perform citizen's arrests on the Zimbabwean leader Robert Mugabe and the former US secretary of state, Henry Kissinger. "It's not for want of wishing or trying."

The fact that the Catholic Church in England and Wales chose to meet its staunchest critics yesterday, on the same day that Benedict gave a speech in Rome welcoming his imminent arrival in Britain, is an indication of how rattled senior clerics are at the prospect of having his trip dominated by protests and criticism of the Vatican. But it also shows a willingness to reach out to its detractors in a way that their counterparts in the Vatican rarely do.

Both sides described the hour-long talks as amicable and calm. Terry Sanderson, president of the National Secular Society, used the meeting to give Archbishop Smith a copy of a new book by Geoffrey Robertson, QC – a legal examination of why he believes the Pope should be put on trial for failing adequately to punish priests who sexually abused children.

Mr Tatchell stuck to a similar theme, asking the Archbishop to tell the Vatican to open all the files it has on abusive priests. "The Pope's condemnation of child abuse will not be taken seriously until he opens the Vatican's sex abuse files and hands them to the relevant police forces worldwide," he said. But Andrew Copson, chief executive of the British Humanist Association, said he wanted senior clergy to know the protests will not be aimed at British Catholics or Catholicism "but against the visit of the Pope as a head of state".

The meeting took place at almost the same time that Benedict appeared in Rome and spoke with enthusiasm about his visit to Britain. The last time he spoke directly about the UK was just before the general election, when he called on his bishops in Britain to campaign against equality legislation.

Yesterday, however, he was gushing with praise for a country that many in the Vatican regard as a hostile bastion of anti-Catholic secularism. "I am very much looking forward to my visit to the UK in a week's time and I send heartfelt greetings to all the people of Great Britain," said the German-born 83-year-old, reading a statement in English.

"I look forward to meeting representatives of the many different religious and cultural traditions that make up the British population, as well as civil and political leaders."