Is the Pope Catholic?

Kathryn Jean Lopez's posts at National Review's blog ususally read like the diary scribblings of a 13-year-old girl, so I typically just glance over them. But this one caught my eye:

An e-mailer rightly corrects my description:

This institute makes no claim to be "Catholic", as its website makes clear. In fact, very few of the articles it produces are written by Catholics. Lord Acton was, of course, not a Catholic and his ideology was typical mid-19th century liberalism.

That said, at the heart of what Acton does is clarify and promote subsidiarity, which is at the heart of much Catholic economic thought. But they do not claim to speak for any church.

Really, Lord Acton wasn't Catholic?

Bill Buckley must be spinning in his grave.

UPDATE: Someone has corrected here, and she has posted it.