Blair's wife and children are Catholics, but he isn't quite. He goes to Mass with them, but hasn't actually made the jump, possibly for political reasons. It is said there could be constitutional problems having a Catholic Prime Minister, because of vestiges of anti-Catholic laws. This probably technically isn't so (unlike the case with the Queen or her successors), but it might have been embarrassing, for example, when the Pope came out against the invasion of Iraq as being an unjust war.

Charles Kennedy is Lib-Dem leader. He's a Catholic. So for that matter was Iain Duncan-Smith.

In the unlikely event that Michael Howard became Prime minister he'd be the first practising Jew to have the job. Disraeli was actually Church of England.

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Actually I suspect the choice of the Oratory for young Blair may well have been because when you are living in Downing Street, it's a lot closer than anywhere in Islington, where he used to live. So the appropriate charge that time wouldn't so much have been hypocrisy but counting his chickens before they were laid, since at the time, he wasn't living in Downing Street. Still it would have perhaps been a bit silly of him to plan on the assumption he was going to lose in 1997. but it was a pretty safe bet Labour was going to win.