The bookies say Boris Johnson is heading for victory – but luckily they keep getting it wrong

At one point on the night of the last US presidential, Ladbrokes took £120,00 on Hillary Clinton to win at 1-6. That turned out to be a huge win for the betting company

It’s bad news for Britain if the betting markets have called it right.

Boris Johnson is the worst prime minister this country has had the misfortune to witness, but he’s odds on to emerge from the forthcoming general election with the majority he craves.

So is it time to say cheerio to the NHS, the welfare state and the economy and hello to five years of nasty hard right wing government that could very well end with the break up of the United Kingdom? For those horrified at that prospect, here’s a crumb of comfort for you: the betting markets don’t always get it right.

The early odds are informed by bookies’ research, polling data, and the feel of their experts, who are political junkies one and all. They’ll start to move in response to developments during the campaign and as the punters money comes in.

Information from battleground seats will also feed into the big picture. Paddy Power has already priced up a list of “hot seats” including Derby North, currently held by the suspended Labour MP Chris Williamson; Gloria Del Piero’s constituency of Ashfield; Putney, held by outgoing Tory rebel Justine Greening; and Portsmouth South, where Stephen Morgan became that constituency's first Labour MP last time round.

The Tories are favoured to win all of them. If that changes, their prospects of securing a majority will look dimmer.

At the moment, a Conservative majority is still the favourite outcome overall, but a narrow one at 10/11. Despite Johnson’s party enjoying a handy poll lead, the odds imply a chance of only a little bit better than 50 per cent. Another hung Parliament is a best priced 11/10, or just under 50 per cent. Every other outcome, including a Labour majority, is a long shot. If Labour had a decent leader it might be different.

The spread betting markets, however, are saying something slightly different. The mid point of Sporting Index’s spread is 324 Tory seats – an improvement on the current tally, but still just short of an overall majority. Johnson is still a nailed on 1/6 to win the most seats, an 85 per cent chance (but more about 1/6 racing certainties later).

There is a theory that suggests you should look at these odds before the polls because betting markets are better at predicting outcomes. People can lie to pollsters and there is plenty of evidence to suggest that they do. This explains the phenomenon of "shy Tories". For a number of years polls underestimated Conservative support, which says quite a lot about the way the party is perceived and perhaps about its voters too. When people are putting real cash at risk, however, they’re inclined to be honest.

But even though political punters tend, as a group, to be savvy and well informed, they don’t always get it right. They didn’t with either the EU referendum or with the last US Presidential election. Leave and Donald Trump were both the outsiders in their two runner fields.

I covered the betting on the 2016 US poll closely. Hillary Clinton had the most money backing her, but Trump attracted far more bets by number, mostly from smaller punters. Partly that was because he looked like value when he was as far out as 9-2 and smaller punters tend to shy away from odds on shots. It’s not much fun putting £50 down to get £15 plus your stake back. But maybe they were on to something.

I spent the evening of that election with Ladbrokes – and a crazy evening it was too. Clinton’s odds had drifted in the run up to polling day while Trump’s contracted, but she was still a strong favourite. Shortly after the polls closed she looked to have knocked it out of the park. Her odds came in dramatically as the money poured in. At one point Ladbrokes took £120,00 on her to win at 1-6. There’s that price again. It turned out to be quite a result for the bookie.

Bets like that squeezed the price to as short as 1-8 at the night progressed. At that point Matt Shaddick, head of political betting at Ladbrokes, was ordering his cab and I was getting ready to for the pleasure of a drive down a nearly empty A406. Then the results started filtering in from the battleground states in the Mid West, and Florida, where Trump was doing far better than the polling had suggested he would. The cab was cancelled and I was texting my wife so she wouldn’t be alarmed at my absence from the house at 4am, by which time the odds were starting to favour Trump.

It wasn’t long after that he was home and hosed.

Electorates around the world are volatile, and right now Britain’s is especially so. It has more floating voters than ever before. Punters’ views are, meanwhile, often shaped by the echo chambers in which they live. Emotion plays a role, too.

Going big on a Johnson victory, at this stage, would be a dangerous thing to do.