apparently stamp duty has changed. By my maths, if you're under £500k purchases you're better off. Over £500k worse off with no real change at £500k itself.
http://www.bbc.co.uk/news/live/business-30249297
http://www.bbc.co.uk/news/uk-politics-30291460
edit: My maths was a little out. The above is true in that no real change at £500k, or the £250k threshold, but the tipping point is more like £1m beyond which you are definitely worse off.