Contact HR for feedback to see what you can improve / polish. Keep reading this thread, keep finding out more about Network Rail and signalling. Tweak your CV and answers to the 69 questions, get someone new to have a fresh look at both if you can.
Keep your eye out for any future signaller jobs in your area, signallers will still retire, leave signalling, leave Network Rail and pass away. Plus the next round of Future Opportunities is scheduled for later in the year. I am in the same boat as those who have been knocked back today (for a non future opportunities signalling role).
Yes it’s frustrating but I am even more determined to be successful next time. Or the time after, or the time after that. Chin up.