The Greater London Authority Elections Rules 2000

Voting procedure (CMER rule 32, LMER and MER rule 33)

7.  The same copy of the register of electors may be used for each election and one mark may be placed in that register to denote that a ballot paper has been received in respect of each election; except that, where a ballot paper has been issued in respect of one election only, a different mark shall be placed in the register so as to identify the election in respect of which the ballot paper was issued.