I canvas in a rural ward, about half of voters are postal voters, many have adult children living with parents, and where one is postal, usually all are postal.

I canvas in a rural ward, about half of voters are postal voters, many have adult children living with parents, and where one is postal, usually all are postal. It's quite easy to see how a secret ballot can be not secret if the (typically patriarch) says "lets fill the forms out together and I'll take them all in"