The form acts as a bridge between a medical examiner (a government doctor) and the employing entity (Public Service Commission or specific government agency), certifying that a candidate is physically and mentally capable of performing the duties associated with a specific office.
If you already hold a HGV or PCV licence and your medical is due for renewal, you will likely need a GP69 . If you are applying for the first time, you need a D4 . gp69 form