I found this <i>ex post facto</i>-ing, so I dug up a relevant link: <a href="http:&#x2F;&#x2F;news.bbc.co.uk&#x2F;2&#x2F;hi&#x2F;business&#x2F;8496921.stm" rel="nofollow">http:&#x2F;&#x2F;news.bbc.co.uk&#x2F;2&#x2F;hi&#x2F;business&#x2F;8496921.stm</a><p>The law in question is the Finance Act of 2008.