“Today, Thursday 15 March 2012, a written ministerial statement has been laid in Parliament outlining a number of changes to the Immigration Rules. Most of the changes will come into effect on 6 April 2012. Some of the changes to Tier 2 will affect those who were granted leave after 6 April 2011.”
UK Border Agency, 15th March 2012
Source: www.ukba.homeoffice.gov.uk