"37 Days" - Where were our spies?

The BBC drama "37 Days", shown over three nights, was a brilliant narrative of the days leading up to WW1. It was fascinating as it alternated between the politicians in London and the German hierarchy. The writing was superb and the ensemble acting first class. I found it totally absorbing and it should be shown in every school in the world on the off chance that something so complicated might be avoided in the future. The political machinations of 1914 had uncomfortable similarities with what was happening now in Ukraine.

But I did wonder when only in the last couple of days, someone realised that Germany had already built half mile platforms on stations close to the Belgium border. Where were our spies?