This has probably been going forever, but I'd never noticed it. Time to have a chat with friendly gold card holders I know...
From the website:
When you buy an Annual Season ticket at a station within the Network Railcard area and the origin and / or destination are also in the Network Railcard area, you are automatically issued with an Annual Gold Card - you'll know if you have one.
One of the benefits of the Gold Card is that holders can buy a Network Railcard for another adult for just £1. This Network Railcard gives up to 1/3 off leisure travel in the Network Railcard area.
How can I buy one?
To buy a Network Railcard for £1, the Annual Gold Card holder must complete the Network Railcard application form on behalf of the nominated person and take it to a staffed ticket office at a train station within the Network Railcard area.
Network Railcards are valid for one year and only one £1 Network Railcard can be issued during the validity of the Annual Gold Card.
The standard Network Railcard terms and conditions of use apply to the £1 Network Railcard