This is of minority interest, but if I put it here it becomes findable…
There is a bank of ticket machines at Cambridge rail station and they will sell you tickets. Some tickets. If you have a Network Railcard (valid after 1000) and you buy a ticket to London at 0945 the machine lets you select your ticket and click Add Railcard but it won’t let you select Network Railcard because it’s ‘not valid at this time’. Except it will be valid when you get on the train, which you are about to do. Someone, somewhere, has hard coded this logic and it’s annoying especially if you’ve got to the station early to avoid the queue.
However today Maria, who is a station marshall, showed me a workaround. If you select ‘travel in future’ you can select TODAY as the future day you’re going to travel on and give it a train time AFTER 1000. Then when you’ve selected your ticket it will offer the Network Railcard option.
I hope this helps. It helped me.