Representation of the People Act 1983

38 (1) The presiding officer, on the application of a voter—

(a) who is incapacitated by blindness or other physical cause from voting in manner directed by these rules, or

(b) who declares orally that he is unable to read,

shall, in the presence of the polling agents, cause the voter's vote to be marked on a ballot paper in manner directed by the voter, and the ballot paper to be placed in the ballot box.

(2) The name and number on the register of electors of every voter whose vote is marked in pursuance of this rule, and the reason why it is so marked, shall be entered on a list (in these rules called " the list of votes marked by the presiding officer ").

In the case of a person voting as proxy for an elector, the number to be entered together with the voter's name shall be the elector's number.