18(1)Immediately before the commencement of the poll, the presiding officer must—S
(a)show each ballot box proposed to be used for the purposes of the poll to such persons (if any) who are present in the polling station so that they may see that each box is empty,
(b)place the presiding officer's seal on each box in such a manner as to prevent it being opened without breaking the seal, and
(c)place each box in the presiding officer's view for the receipt of ballot papers.
(2)The presiding officer must ensure that each box remains sealed until the close of the poll.