Tomorrow is a special day for people like me, as someone who loves a bet - and for lots of other people, too. It is Grand National day – the one day of the year when millions of people who otherwise wouldn’t dream of having a bet make their annual trip to the bookies and enjoy the same thrill that I get during the rest of the year.

This year, more people than ever will make that trip, and they’ll stake more than ever. Last year, we gambled £150 million on the outcome. Bookies expect that figure to increase to £170 million tomorrow. And with the FA Cup semi-final on the same day, it’s likely that the total sum gambled will be over £200 million - by far the largest amount ever bet on a single day.

As a country, we’ve changed our attitude to gambling. Until relatively recently, those of us who bet regularly had something of a guilty secret. When I was a kid, I would stand waiting outside the bookies while my dad put his – and my – bets on. One year, I took part in a general knowledge competition for London cub scout packs. The tie-breaker was: where is Mecca? I confidently gave my answer, from my weekly wait outside the very place: Northwood Hills.

The looks on the other parents were telling: what kind of upbringing must I have had, to be subjected to such a thing!

Today, it would provoke nothing but a laugh. The National Lottery changed all that: making the idea of gambling respectable to the middle classes.

But whilst betting may now be a far more widespread passion, it is not a homogeneous affair. There are set types of gamblers who will put their money down tomorrow. Anyone who has worked in a bookies, as have I, can spot them a mile off.

First, and by far the most numerous, are the Once-a-Year punters. They don’t really approve of gambling: it’s not a very sensible thing to do with your hard earned cash. But they’re not puritans, and like to let their hair down once in a while. It doesn’t do any real harm to have a bet on the National, so Dad will go off to the bookies and put his couple of pounds each way on the whole family’s selections.

The way people bet says a lot about the way they lead the rest of their lives. The once-a-year punters are the same in the rest of their life. They're the people of whom you gossip: "She never really gets drunk, and he doesn’t really like to draw attention to himself. But you should have seen them on the dance floor at that wedding!"

The second group are the Eternal Optimists, known to the bookies as Mug Punters. On a normal day, they are the most numerous. They don’t claim to be experts about racing but they like a flutter and they’ve heard from a friend who’s heard from a mate whose boss’s wife sat on the train next to someone whose builder worked for someone who owns a horse which has been ‘laid out’ for the four o’clock at Towcester. So they put a hundred quid on the nose and spend the day counting their expected winnings. The Mug Punter's horse falls at the first. A little learning is a dangerous thing.

They are quite likely to have the same attitude in the rest of their life. Take a bit of a chance here and duck and dive a bit there. They’ll go out for a drink after work, having promised to go straight home, and think they’ll get away with it.

Finally, there are my friends and I: The Experts. We spend hours poring over the form book, working out which horses perform best on firm ground, which on soft, what difference an extra pound or two in weight will make to their running, and whether they are tired or fresh after their last run. We look down with smug superiority on the Once-a-Year brigade, who opt for horses ridden by jockeys they’ve heard of, such as Tony McCoy, or names which take their fancy. What fools! Don’t they know that every time they strike such a bet they are simply contributing to the Bookies’ Benevolent Fund? They can’t hope to compete with the in depth knowledge which I and my fellow obsessives have garnered!

Fat use it is. If we Experts knew as much as we think we do, well…I wouldn’t be writing this. I’d be at Aintree, preparing to see one of my string of racehorses running tomorrow, before taking my helicopter back to my mansion.

The phrase is ‘self-delusion’. We like to think that we can somehow interpret events and turn them to our advantage. But we are, of course, mere mortals. We might know which horse the form book tells us will win, but that doesn’t take account of one vital ingredient: luck. And we are ever so slightly odd: we can be happier sitting alone with our heads buried in yesterday’s results from Musselburgh than chatting with friends.

We’ll see who wins tomorrow. But – I didn’t say this, OK? – the once-a-year punters are just as likely to win as the so-called experts. Take the winner in 1992. That year, the National took place in the middle of a general election campaign, so one horse in the race was heavily backed because of his name: Party Politics. We experts snorted our derision.
He won.

If you like betting on names and co-incidences, how about Red Striker to win? For what it’s worth, my money’s on Clan Royal. But what do I know? I’m only an expert.