Tony Blair has revealed how Catholics were excluded from holding the position of Ambassador to the Vatican by the British government from the time of the Reformation until he overturned the ban.

Successive British governments believed that Catholic ambassadors would be too close to the Pope and not offer good advice.

Blair, a Catholic convert, broke the ban in 2005 by appointing his private secretary, Irish-born Francis Campbell, to the job despite major internal opposition.

A new documentary reveals that Blair had to fight tooth and nail to get a Catholic appointed.

In the program “Our Man at the Vatican” to be broadcast by the BBC, he hits out at the decision to ban Catholics from the post of British Ambassador to the Vatican as “ridiculous” and “discriminatory.”

“One of the funny things about the 'Yes Prime Minister' show (a popular TV show where public servants blocked much of their leader's agenda) is that, if you have actually done the job, you realize there is parody but, my goodness, it is parody close to truth,” said the former PM. “And one of the great Sir Humphrey moments was when the Ambassadorship to the Holy See became vacant.

“I said ‘Well, Francis would be a great person to do that’. And they said ‘Well, you know this, Prime Minister, but actually, we don't really have this open to Catholics.’

“I honestly thought I misunderstood what they were saying.”

 Blair added: “I said ‘It's the Vatican. The Pope, he's a Catholic. You mean we actually as a matter of policy . . . say you can't have a Catholic . . .It's the most ridiculous thing I have ever heard.’”

Blair said he told civil servants: “I don't think that is very sensible — not in this day. Quite apart from being discriminatory, how stupid is it?” He added: “So Francis was the first.”