I’ve spent some time this week pondering the protagonists of my preferred genre, the action thriller. In my odd moments over the past month I’ve read several enjoyable examples, some of which have been truly excellent; but I find myself returning again and again to my routine gripe: is it really necessary that the male lead in almost every one should be an ex-SEAL, CIA-trained mega spy with a vast personal fortune, a Jeremy Clarkson-esque knowledge of fast cars and an advanced engineering degree?

It’s become so strong a type in the genre that it’s an automatic reflect to suspend our disbelief unhesitatingly, as if it were quite normal that every person who happens to come into contact with a sudden bout of terror or hype would — obviously — be able to fall back on just such a set of circumstances.

But I’m not so sure. We seem to be asking ourselves to believe a little too much, just for the sake of a convenient story. What would really happen if a man walked into a situation, any situation, and made it known that he fit this strange bill?

Funny you should ask.

This week, I determined to find out. My target: a lovely little coffee shop I often frequent, sitting with my computer and far too much caffeine when I require a bit of background noise to keep the keystrokes coming. I don’t often chat with people there (I’m usually absorbed in writing), but on this occasion I determined to change that.

I walked in, calmly, purchased my coffee, located a table and sat down.

‘Hello,’ I said to the young man at the table next to mine. He was perhaps twenty-three, wore good, educated-looking glasses and was reading a copy of something by Sartre.

‘Hello,’ he answered, understandably surprised to be interrupted in this way.

‘It’s just that you looked as if you could use a little help,’ I said, as thoughtfully as I could.

‘Did I?’ The man surveyed his table, wondering, perhaps, if he’d inadvertently spilt something.

‘You’re reading Sartre, which is usually a sign of someone in mental distress,’ I replied, motioning towards his book. ‘Possibly angry, depressed, suicidal.’

‘I’m not sure what you think that–’

‘And I just wanted to extend my help,’ I cut him off. ‘We learned all about intervention and rescue during my SEAL training.’

At this point, the baffled young man, who at first at seemed taken aback at my characterisation of his choice of coffee-shop reading, now seemed more curious about my sudden self-revelation.

‘You were a SEAL?’

‘Only for seven years. My contract with the CIA wouldn’t allow a longer term leave of absence. But fortunately for you, our surveillance training for the Agency helped us see signs of mental deterioration and distress in hostage situations, so I can put that to use with your crisis, as well.’

‘I’m not in distress, or a hosta– wait,’ the man caught himself, ‘you were both a Navy SEAL and in the Central Intelligence Agency? Despite the fact that you’re very obviously British?’

‘I had to do something with myself,’ I answered, taking a sip of my latte. ‘After my father died and left me his two-billion pound company and estate, I had to make good. I knew I couldn’t run the firm, but I was set for life. Can’t just sit around when you’ve been given a gift like that. Have to find honour, courage. You know . . . those to whom much has been given.’

‘You did all that, and yet you still know about Sartre?’

‘We had to read him at Yale. Graduating summa cum laude and valedictorian doesn’t come without a little philosophy.’

A touch of indignance. ‘Sartre wasn’t really a philosopher, he was an existentialist playwri–’

‘But it was during my six months as a POW in Iraq that I really saw through his depressing vision,’ I added. ‘Not the book you want to have with you in a prison camp, let me tell you.’

By this point, the young man had set down his copy of Sartre and turned himself fully towards me.

‘You were a prisoner of war?’

‘Yeah. Bum luck. Managed to escape though, by cutting out of my cell and re-wiring a dilapidated Italian Army transport truck the Iraqis had stolen from the Allies and left just outside the camp. Not the most advanced engine to re-build with tools I found around the grounds.’

There was a fairly substantial pause in our conversation at this point, during which I drank a bit more of my latte and answered a brief SMS message on my phone.

Finally, the young man looked right at me and spoke.

‘Bull shit, man. That’s utter bullshit.’

He said these words with such utter conviction that for a moment I thought he might actually be sincere in disbelieving that I was an ex-SEAL, ex-CIA, Yale summa cum laude valedictorian, escapee-POW with a powerful knowledge of auto mechanics and chairmanship of a multi-billion dollar company I’d inherited from my father. With a strong working knowledge of the existential crises posed by the stage plays of Jean-Paul Sartre.

But then I realised that this was just as believable as the back-story of the lead characters in 80% of the thriller fiction I’ve ever read, and decided instead — quite reasonably, I think — that the young man was simply mad.

After all, he was reading Sartre in a coffee shop.