As members of the public were invited to see Benedict XVI regardless of their faith, it emerged that he will meet Nick Clegg, who is an atheist, and Harriet Harman, whose Equality Act angered the Church. The Government is keen to portray the four-day state visit as a historic event that will enhance the country's standing worldwide and to highlight the pontiff's commitment to social justice, in order to head off criticism over the costs and the child abuse scandal affecting the Vatican.
Lord Patten, invited by David Cameron to oversee the planning, said that the significance of the first-ever state visit by a Pope to Britain was greater than the potential costs.
He told a press conference: "Even if we had known of the parlous state of the nation's finances, I'm sure that wouldn't have been a consideration because the importance of this visit makes its own claim upon modest public support."
The last governor of Hong Kong said Britain was not returning to the Middle Ages "or the days when we would have had to find a squirrel for the pot".
He said he himself had never felt "second-class" as a Catholic in Britain but that if anyone has, the pope's visit will end that feeling.
As The Daily Telegraph disclosed on Saturday, the cost to taxpayers of the event in September is now put at up to £12million, excluding undisclosed security costs, up from £8m.
The church claims it has now raised about £5m of its initial estimate of £7m for the pastoral parts including open-air masses in Glasgow and London and the beatification of Cardinal Newman at a park in Birmingham.
But the Most Rev Vincent Nichols, Archbishop of Westminster, insisted that these events are not just for Roman Catholics, even though parishes are organising tickets for the "pilgrim journey".
He said: "These are events to which any person is welcome. All they need to do is contact their local Catholic parish."
It also emerged that the Pope will visit an old people's home - one of the suggestions in the notorious Foreign Office memo that mocked Catholic teaching - and meet political leaders including the Prime Minister, the Deputy Prime Minister and Labour's acting leader.
The National Secular Society, which opposes the papal visit, estimates that the security costs of the trip will increase the burden on taxpayers tenfold.
Its president, Terry Sanderson, said: “The NSS is outraged but not surprised by the news that the cost to the taxpayer of the Pope’s visit is spiralling towards £100 million. We predicted this would happen at the very beginning, although the previous Government denied it."