I saw the programme, and having had 20 years of NCTs I'm stunned that this can even happen. I've had a car that was marked as unroadworthy because of damage to a tyre sidewall (notwithstanding the fact that there's a spare tyre in the boot that can immediately replace the problem tyre), I know someone else who had a similar experience with brakes that suddenly failed at the NCT centre, and my father had a car that failed the NCT for rust issues to the body that he couldn't get a single mechanic to even quote for and had to scrap the car. In at least a couple of cases NCT turned up an issue that was undiagnosed previously that went on to show a more serious issue. I've literally never been to a test centre that didn't do a proper visual check (aside from one small country centre that took a very cursory glance at some lights).
It suggests that "trade" or other individuals are able to extract favours from within the system and that's horrifying. It means the integrity of the entire system is under question.