Here is what it says about how an elector should mark his/her ballot paper:
(1) In Schedule 1 to the 1983 Act (parliamentary elections rules), after rule 37 there is inserted—
“How votes are to be given
37A (1) A voter votes by marking the ballot paper with—
(a) the number 1 opposite the name of the candidate who is the voter’s first preference (or, as the case may be, the only candidate for whom the voter wishes to vote),
(b) if the voter wishes, the number 2 opposite the name of the candidate who is the voter’s second preference, and so on.
(2) The voter may mark as many preferences (up to the number of candidates) as the voter wishes.”
This isn't good enough. There will be some voters who choose not to use their lower preferences and will continue to mark their ballot using the traditional 'X'. Their vote should be valid, and be considered to be the same as a number 1 with no other preferences.
Some voters may accidentally miss out a number, e.g. mark their preferences with the numbers 1, 2 and 4. Mistakes like this should not invalidate the ballot, and the preferences should be reallocated as if the 4 was a 3. The bill doesn't make this clear.
Some voters may even do unexpected things like mark their ballot papers with fractions, or roman numerals. It needs to be made clear that these ballots, when a clear numerical preference has been shown, should be considered valid.
I fear that the rules laid out in the bill as it stands are too prescriptive, and will lead to ballot papers being wrongly rejected.