Hmm, I went in 2008 when the exchange rate was almost exactly $2 AUD to 1GBP. Maybe that has something to do with it? I don't remember thinking "wow, that was an expensive pint" and I definitely would have, as I was living on a food budget of $20 - $30/week.
I suppose if I'd paid $6 for a beer back in 2008, that would have been £3. but today you'd be looking at more like £4.50?
I went in 2009 when it was 2:1 as well. Prices in £ are a LOT higher now than they were then. Don't forget inflation on top of exchange rate fluctuations, plus I'd imagine some tax hikes on alcohol. The change in exchange rate has been much more marked than between the pound and dollar for example. Unless there is a drastic change in exchange rates I can't see myself going on holiday there again for the forseeable future.