According to UKBA, following Parliamentary approval, there will be an increase in fees for visa applications made from overseas and applications made from within the UK from Saturday 6 April 2013.
All applications submitted from 00:01 (UK time) on Saturday 6 April, must be accompanied by the correct fee. Any application accompanied by the old fee will not be accepted. Applicants can use an old version of an application form for 21 days following the increase, but these should be accompanied by the new fee. New versions of UKBA application forms will be available on their website.