From 1st October 2012 if you have overstayed your leave by more than 28 days, the UK Border Agency will reject your application for further leave.
This change in the Immigration Rules will affect applicants applying for further leave under: the points-based system; all working and student routes; visiting routes; long residency routes; discharged HM Forces; or UK ancestry routes.
This change is in line with the new immigration rules which will come into effect for the family migration route from 9th July 2012.
If you have limited leave to remain you must ensure you apply to extend your leave, if needed, in time.
If you wish to remain in the UK after the 28 day period you should leave the UK and reapply for a visa.