Most of it will simply be profit and from what I can tell all of the "Big Three" have done the same. To the sort of people who are prepared to remortgage their home it probably won't make a huge difference. In 2006 when prices were about £60k, someone who left school, got a decent job and saved up could probably manage it to afford it by their late twenties.
Like most things, I think it will ultimately change, I think a big question is the timeframe within which that will be the case.