Grandmabatty If your mother gets a postal vote, she will get round the visual identification filter. When he was not able to get to the polling station, my husband applied for one, and I did too, at the same time. I have used it at every election for the last ten years.
Your ballot paper is delivered by the postman, a couple of weeks before the election, along with detailed instructions how to seal it into the envelope so that it can be verified as coming from you, and you post it back to them to arrive before polling day. No need for extra identification, your signature is enough.
However, that doesn't sort it out if it then becomes common for other things to ask for photo identification.