If you have a visual impairment, a physical disability or a literacy difficulty that prevents you from voting without assistance, the Presiding Officer can help you cast your vote. If you chose the Presiding Officer to help you vote, you should go to the polling station well before the polling station is closing. The law allows a Presiding Officer to refuse a request for assistance during the last two hours of voting if in helping one elector to vote would prevent others from voting.   If voting this way, the Presiding Officer and any personation agent present goes to an area of the polling station where they would not ordinarily be overheard, for your privacy. If required, the Presiding Officer can suspend entry and have the polling station cleared to ensure privacy and the secrecy of the ballot. (This facility is why there is the provision whereby returning officer can refuse assistance in the last two hours of polling).   The Presiding Officer asks how you want to vote and marks the ballot paper according to your preferences. The law forbids a Presiding Officer from acting on any written instructions received from a voter. This is to ensure that Presiding Officer is acting upon your wishes and that there has been no interference from a third party.