It was always a case of `could try harder' with the news anchor - until he met a man-of-mystery English teacher and a lorry driver who helped him to cram.
The words most often repeated in my school reports were "could try harder". I think the last one read, "He sets himself low standards, which he then fails to achieve."
I wasn't particularly naughty but I was a bit of a rebel. My preparatory school in the late 1950s, the Pilgrims' School in Winchester, had few resources so we had to amuse ourselves. We'd put on exhibitions of bits of rock and I ran the school magazine, which was all carefully drawn by hand. It was called the Daily Trumpet but it was never daily. That would have been too big a production exercise. I was always busy. I just wasn't busy doing the things the school wanted me to.
I was languishing at the bottom of Class 4a when I met Rodney Blake. He taught me English from the ages of 9 to 11 and was the only teacher who ever inspired me to get involved in the subject.
He told me about adjectives and developed my love of descriptive writing. He let my essays flower and taught with encouragement, never with threat. By the time Mr Blake had finished with me, I had learned everything about grammar. I can trace my desire to be involved with the English language from that point.
Mr Blake was a man of mystery. He was about 35, a generation younger than the other teachers, and he'd done war service. When he talked of the navy, we boys thought of James Bond, so we used to think he'd been some kind of secret agent. He had what appeared to be an extremely small war wound, which was a pinhole in his index finger. He never told us it was a war wound - we just decided it fitted the picture.
At 13, I left Pilgrims' where I had been a chorister, and went to St Edward's School in Oxford where I failed to achieve much. I think I left with four O-levels and a C in A-level English, which was thanks to Mr Blake.
I then went to Scarborough Technical College - my family had moved to the North of England by then - and met another man who would have a great impact on me. Bob Thomas was a teacher and long-distance lorry driver, and his job was to get me through my A-levels in a year.
At this point my father, who had been a headmaster and was now the Bishop of Whitby, was considering putting me in Dorman Long steelworks as an apprentice. That struck me as heavy weather, so I knew I had to get some A-levels and go to university. Mr Thomas made me feel as though I was a superbrain and that kick-started me into some sort of activity.
I got my A-levels, albeit with poor grades - a D in economics and an E in law - and crawled into the University of Liverpool through clearing before being chucked out two years later.
I lost touch with Mr Thomas but kept in vague contact with Mr Blake. Shortly after I left Pilgrims' he became headmaster and then ran off to New Zealand with the piano teacher. It didn't work out and he went off the rails. He had something like emphysema and it was a miserable end. Just before he died I spoke to him on the phone: I told him how much he meant to me and this pleased him. By this point, 15 years ago, I was already doing Channel 4 News.
When I look back, I thank Mr Blake for sowing the seed and Mr Thomas for reaping it. From the shambles, they managed to retrieve the man I became.
Jon Snow is an ambassador for Ambitious about Autism. The charity has launched a campaign called Ruled Out: why are children with autism missing out on education? For details, go to www.ambitiousaboutautism.org.ukruledout He was speaking to Kate Bohdanowicz
ON THE NEWS TRAIL
Born: 28 September 1947 in Ardingly, Sussex, England
Education: The Pilgrims' School, Winchester; St Edward's School, Oxford; Scarborough Technical College (now Yorkshire Coast College); the University of Liverpool (sent down at the end of the second year for organising an anti-apartheid protest)
Career: Broadcaster, newsreader and anchor for Channel 4 News since 1989.