Imagine that all your life you have been aware of a great conspiracy that everyone is part of - except you. Worse, you can't reveal you aren't part of it. If you did, your life would hardly be worth living.
It's the stuff of nightmares but it has been real life for John Bradbury and thousands of others.
For most of his 69 years, John could not read or write. He has had to remain unseen, unknown, unheard from. "I'm the bloke who always stands at the back," he says ruefully. "If you push yourself forwards, you never know when someone might want you to read or write something.
But in the past three years, everything has changed as he at last learned to read and write in adult literacy classes at South Thames College's Tooting site.
Before this recent, happy period, the world was a daunting place. Simple things became complicated. It was hard, for example, to travel further than he could walk as you have to be able to read signs and maps to use public transport. "I didn't use the tube very often," says John, who was born, and still lives, in West London. "You could jump on if you were only going one or two stops. Otherwise you could only go if you had someone else along with you."
Driving, John found, requires words too. He took his test in 1959 - long before the written part came in - but while others worried about hill-starts and three-point turns, he was fretting about filling out the simple form at the test centre. "I practised for ages writing my name before I took that test."
Shopping was another challenge. "That's where I used to feel very vulnerable. Loose vegetables were all right, but for packets and tins you had to look at the pictures to guess what was inside. I've had some real surprise dinners that way." Once he gets the ingredients home, recipes were an impenetrable mystery too. "I just have to make my own up and hope for the best," he says.
Creating his own recipes is just one example of the many ways John has circumvented the difficulties of living in a literate society. He beat the transport problem by becoming self-reliant. "I had a bike, then a motor bike, then I got my own car." Navigating was never easy, but John could always read numbers so, while others set out for "Bristol", John would head for the M4.
The other weapon that helped him to keep his condition secret for so long was avoidance. "You just make excuses all the time, the most usual being, 'I haven't got my glasses.' Then you might say to someone, 'You do this, I've got drops in my eyes.' The one thing you don't do is admit it."
Denial started early for John. "When I was a kid, if you couldn't read or write you were classed as an idiot."
The youngest of five children, John soon realised he was "a bit different", but even at primary school was already developing strategies to cope.
"I don't know how I did it, but I always had a good memory, and I learnt a whole page by heart of one book. If I was called on, I would just recite that page. I knew I couldn't read. I think they knew too, the teachers, but they didn't do anything about it."
It was a painful time, literally: John used to get the cane at regular intervals. "If anything went missing I seemed to be the one they picked on.
Because they thought of you as an idiot, they just pulled you in."
"Idiot" is a word John uses often when he talks about his early life.
Others made him feel idiotic too on the games field. "I don't know if it was all part of the same thing, but my co-ordination was bad as well. At football, I was always the last one to be picked."
John tells this all matter-of-factly, with little sign of resentment. When he was eventually sent to a special school - where he shone at woodwork - he was told to forget about ever trying to learn to read: "We only bother with those who can do a bit already. With the rest we don't bother."
How did that make him feel, being constantly knocked back? "Well," he says philosophically, "I suppose I felt a bit inferior." Then he smiles. "But only a little bit. After all, there's lots of people in the world who've had it worse than me."
In many ways, John has coped admirably. He has had a successful career as a self-employed carpenter - his wife did the books until she died in the late seventies - and brought up his children, all of who are now prospering.
After a number of false starts he has made his big breakthrough in recent years, beginning at last to learn to read and write at South Thames. He has also started to travel abroad, his new-found confidence enabling him to negotiate his way around the once-feared airports. And now he has his own computer, which he uses to word-process a whole variety of writings.
These remarkable documents chart the highs and lows of learning what everyone else learnt 60 years earlier than him. "Sometimes," he writes, "we all like to feel important. It makes us stick our chests out and feel great... until you fall off your perch and come back down to earth."
Tellingly though, in that same piece, he makes it clear that he's not going to be 'off his perch' for long. Since starting at college, he writes: "I am slowly beginning to climb the mountain. The sun is starting to shine again, and spring is just around the corner."