As soon as practicable after the issue of each batch of postal ballot papers, the returning officer shall make up into a packet the counterfoils of those ballot papers which have been issued and shall seal such a packet.

As soon as practicable after the last batch of postal ballot papers have been issued, the returning officer shall make up into a packet the marked copy of the absent voters list and the list of postal proxies and shall seal such a packet.

Until the time referred to in paragraph (2) above, the returning officer shall take proper precautions for the security of the lists referred to in that paragraph.