FoFNL member Frank Faulkner has been in touch with this information:
As a Hearing Aid wearer I was surprised to learn recently that I qualify for a Disabled Persons Railcard and this seems not to be generally known.
Although it offers the same ⅓ discount as my previous Senior Railcard it has other benefits, the most important of which is that its use is not time-limited. You can also take another person at the same discounted fare - and it's cheaper! I applied online and received my railcard three days later.