Have not read the report yet, but were they NR staff or Contractors ? we sometimes have real issues with non NR staff, recall a few years ago, we had a request for a line block, when they were asked for their location, the Signaller got the reply 'Behind Staples' ! We also had (again sometime ago now and investigated) staff with a valid block, which was on and off for sometime during the day (Sunday) , in the end they needed one more, told to wait for a train to pass, which it did, no call, 15 mins went by, in the end Signaller called them, no train had passed, alarm bells rang, asked to verify location, which was correct, however after a long pause, said, sorry we might have got that a bit wrong, ended up they were 15 to 20 miles away, and beyond another junction, AND had the wrong line too ! needless to say, removed from job, screened, investigation, disciplined, and more think they had all the wring documents etc, just used the wrong one for that job!