F1SI 1985/454
46(1)Any ballot paper—
(a)which does not bear the official mark; or
(b)on which the figure 1 standing alone is not placed so as to indicate a first preference for some candidate; or
(c)on which the figure 1 standing alone indicating a first preference is set opposite the name of more than one candidate; or
(d)on which anything (other than the printed number on the back) is written or marked by which the voter can be identified; or
(e)which is unmarked or void for uncertainty,
shall be void and not counted, but the ballot paper shall not be void by reason only of carrying the words one, two, three, (and so on) or any other mark instead of a figure if, in the opinion of the returning officer, the word or mark clearly indicates a preference or preferences.
(2)The returning officer shall endorse rejected on any ballot paper which under this rule is not to be counted and if an election agent objects to his decision shall add to the endorsement the words rejection objected to.
(3)The returning officer shall prepare a statement showing the number of ballot papers rejected by him under each of sub-paragraphs (a), (b), (c), (d) and (e) of paragraph (1) and shall, on request, allow any candidate or agent of a candidate to copy such statement.
(4)The decision of the returning officer on any question arising in respect of a ballot paper shall be final but shall be subject to review on an election petition.