For JA's preference,I mean.

The Goldsmith history that many people assume she is parodying in her History of England is rampantly anti-Catholic, and she really does seem to be trying to say the opposite of everything he says. Whether this really means that JA really had any kind of preference for Catholicism is hard to tell, but I suspect not- it's all part of the teenage fun. Perhaps we should look at Northanger Abbey for pro-Catholic sentiment, too, since most of the Gothick novels were rampantly anti-papist. More serious novels, like Sir Charles Grandison which I have not read, and Elizabeth Inchbald's A Simple Story which I have, deal much more sympathetically with Catholicism and inter-faith marriages, BTW. Now, would JA at sixteen, writing the history, have the same sentiments as at twenty-one when writing P&P? Again, I somehow doubt it. P&P is neither a parody nor a political commentary, as far as anyone has been able to establish. Why then, should anyone assume a connection?

As to whether she implied anything to do with either the Whigs or Catholicism in the use of the name it's even more vague to me. One thing I'm sure of though, is that she couldn't really have applied both. George III was mandated by his coronation oath to uphold Protestantism and fight Catholicism at every turn, a task that he took very seriously. Any overtly Catholic aritocrats did not have much of a look-in in his government, or in his father's before him. So it's difficult to envisage her Mr Darcy as both Catholic and a wheeler-dealer in political circles, at any level.