"How do you distribute a surplus?
The most complex part of the counting process relates to the distribution of surplus votes. When a candidate exceeds the quota on the first count, the second preferences on each of their ballots are examined. The votes above the quota are allocated to the remaining candidates in the field based on the ratio of second preferences which has been determined by the examination of the votes.
After the first count, only the votes above the quota are examined and used to decide the ratio for the allocation of the surplus votes."
Curious... How do they work out which votes are deemed to be the surplus? If they just select the last stacks counted that could influence the transfers as boxes are usually opened in a sequence and the last boxes counted would be from a particular part of the constituency and may favour a particular candidate.