@Graham *****
, you don't lose a day if you apply late, the extension is still 30 days. If your exemption/Visa expires on the 9th of Feb whether you apply for the extension on the 15th Jan or the 10th of Feb (the day after expiry), your extension will still end on March 10th. Applying late just means you are fined, and your extension date doesn't become 29 days instead of 30. It is based on your entry stamps' required exit date.