Tough taxi test made great TV

I had a fair few I’d like to forget, starting with GCSE Maths when, ironically, my inability to correctly read numbers on my timetable meant I wrongly showed up in the afternoon instead of the morning.

Then there’s the dreaded journalist’s shorthand exam – where a sneeze mid-test is fatal as you can’t jot down the near-perfect wording required to pass.

And don’t even mention my shoddy attempts at parallel parking during dense school-run traffic in driving test number one...

But I doubt even those doing a PhD in nuclear physics would find a bigger cerebral stretch than the tests sat by London black cab drivers before they are allowed to negotiate the jam-packed streets of our capital.

The Knowledge (Channel 4)captured perfectly the brain-boggling levels of preparation needed to get through the intensive exams – basically, you have to be the human equivalent of a sat nav in a city which many of us wouldn’t dream of driving in.

I have no clue how anyone can memorise and repeat the thousands of routes and the 25,000 street names candidates were grilled on and the statistics speak for themselves when you learn 70 per cent of applicants drop out. It could have been a dry subject but the documentary came to life with the human stories behind the swotting –some of which took candidates years to master.

Particularly touching was former city worker Paul, whose family’s hopes were all riding on him passing.

He ditched his stressful job to follow his dream of being his own boss and working as a cabbie. It was clear it meant the world to him when he got behind the wheel at long last and picked up his first passengers – and offered them a free ride.