Boris Johnson’s resignation as the leader of the Conservative Party brings an end to one of the most controversial political tenures in post-war history. His domination of the party, and the speed at which events have suddenly turned, have left the field of potential replacements wide open. Eyes are turning to who will become the “dark horse” candidate.

One of the most repeated political “iron laws” is that front-runners (and the bookmakers’s favourites) rarely win the Conservative leadership contest. Since Johnson resigned yesterday, Ben Wallace, Penny Mourdant and Rishi Sunak have been touted as favourites to become the next Prime Minister. So does this now mean that their leadership campaigns are doomed to failure? 

The historical omens are not good for those who enter the race as the clear favourites. The modern era of political betting began in 1963 when Ron Pollard of Ladbrokes offered odds on the Conservative leadership contest to gauge public interest. His initial pricing of the “nearly man” Rab Butler as 5/4 favourite was undermined by the victory of rank outsider Alec Douglas-Home at 16/1. But a few years later, Ladbrokes correctly called the 1965 race. It put Edward Heath as the slight 4/6 favourite over Reginald Maudling at evens. The outsider, the 100/1 Enoch Powell, stood little chance of causing an upset. 

Thatcher’s election created the idea of outsiders winning

The growth of political betting in the 1960s led to The Times breaking with convention and accepting money from gambling firms to run adverts and coupons during election times. The Conservatives’ faith in Heath prevented a leadership contest from taking place as punters broke gambling records during the various elections and referendums in the 1970s. As a result, pricing became an integral part of the political debate. Newspapers reported that bookmakers were “developing friends and contacts up to Cabinet-level” and “becoming political experts in their own right”. 

People enjoyed political betting so much that the eponymous founder of the gambling company William Hill began to worry about how it would eventually corrupt the system and affect the outcome of elections. He warned that “it could become an evil if sensational reports of the odds were published” and “sway public opinion to make people vote according to their stake instead of their conviction”. It didn’t, however, stop him from opening books on who would be the next Conservative leader. 

It was the election of Margaret Thatcher as leader in 1975 that created the idea that outsiders have a chance of winning the contest. In the autumn of 1974, after the Tories lost another election, the bookmakers agreed that Willie Whitelaw was the 5/4 favourite to take over from Heath. Other candidates were Robert Carr (7/4) and the maverick Sir Keith Joseph (4/1) on the right. “Mrs. Margaret Thatcher,” Ladbrokes claimed, “is the 50/1 outsider.”

Even in January 1975, as she openly challenged Heath for the leadership, the betting companies did not expect her to win. Beginning as the 12/1 outsider (the same price as her rival Jim Prior), she confounded expectations by securing the support of over a hundred MPs on the first ballot. By the time of the second ballot she had enough momentum to outstrip Whitelaw.

Fifteen years later, another “dark horse” in John Major surprised the pollsters and the markets with his victory. In the late 1980s, Major had been touted as a natural successor to Mrs. Thatcher. His rise, described by the historian Alwyn Turner a “crash course in statesmanship” saw him hold three of the four Offices of State between July 1989 and November 1990. But as the Thatcher government fell and people such as Nigel Lawson and Geoffrey Howe resigned, there was an expectation that the prize would fall to someone who was openly critical of her leadership. 

Her long standing rival, Michael Heseltine, was quickly installed as the 6/5 favourite when he announced that he would challenge her, while Major was quoted at 14/1. But the expectation that Major would fall in behind the Prime Minister changed when she struggled to win outright on the first ballot. Even then, the bookmakers had Heseltine the 6/5 favourite, with Hurd at 6/4 and Major at 5/2. His eventual victory, in part due to a “stop Heseltine” campaign, would go down in political folklore. 

Major’s premiership in the 1990s would be dogged by constant speculation of a leadership challenge. In the aftermath of Black Wednesday in September 1992, William Hill took a series of substantial bets on him to be replaced before the next election. As Major’s Deputy, Michael Heseltine was again the 4/6 favourite, with Ken Clarke (6/4) and Michael Portillo (12/1) expected to fight it out. 

Nobody in the mid-1990s, however, talked about William Hague. In the wake of the 1997 election defeat, after dozens of leading figures lost their seats, many came to the conclusion that he was the person to revive their image. Heseltine again opened up as the 7/4 favourite to win, but a heart attack stopped him from standing. Instead, it opened the floor to William Hague (3/1), who quickly gathered support behind him. Early outside candidates such as Stephen Dorrell (6/1) struggled to cut through. 

The idea that the front runner struggles to secure victory gathered greater impetus at the turn of the century when the red hot favourite Michael Portillo was beaten by another underdog in Iain Duncan Smith. Throughout Hague’s tenure as leader in the early 2000s the press speculated that Portillo would challenge him for the leadership. After the 2001 defeat, punters quickly backed Portillo into 1/3 to be the next leader.

For all the talk of ‘dark horse’ winners, candidates are usually established before the campaign

Yet stories about his private life, combined with his stark criticism of the party’s approach, rocked his chances. After warning Tory MPs that “we could do even worse next time”, attention turned instead to Michael Ancram to become the leader. Having begun the race at 50/1, punters backed him into 3/1. After all that, it was Iain Duncan Smith (9/2) who eventually won after a long and bitter struggle with Ken Clarke. 

Iain Duncan Smith’s reign ended just two years later in a contest that most bookmakers called correctly. As speculation mounted, the betting companies predicted that the leadership race would generate over £1 million and become one of the biggest political betting events of all time. William Hill concluded that Michael Howard was the clear 11/10 favourite with David Davis (7/2) also having a chance if it went to the members. Future leader Theresa May (16/1) was seen as one to watch out for but was soon squeezed out as the Tories fell in behind Howard without a contest.

It was perhaps the drama of the 2005 battle that finally established the idea that front-runners don’t win. Back then, in the aftermath of New Labour’s third consecutive victory, commentators quickly identified David Davis as the best candidate the Tories had. He was immediately installed as the 13/8 favourite, as papers such as the Sunday Telegraph claimed that “his action-man image gives him populist appeal”. Other MPs, such as George Osborne (11/1) and Boris Johnson (66/1), were seen as too inexperienced for a run. 

Throughout a long summer leadership contest, eyes slowly turned to David Cameron, who had initially opened up at odds of 9/1. In June 2005, the Times had run a poll that showed that only six per cent of the public recognized him. People such as Mike Smithson, the editor of the increasingly influential Political Betting site, wondered whether being an old Etonian still disqualified him from being a Tory leader. 

By party conference, he was still a 12/1 outsider, with Davis ahead with both the voters and the markets. In Blackpool, Cameron famously gave a speech that turned his fortunes around. At the same time Davis floundered. A spokesperson for William Hill admitted that it was “unprecedented that a contender for the leadership should go into a party conference as a 12/1 long shot and emerge at the other end as odds-on favourite”. As a person that few people knew, Cameron tapped into a mood for change within the party. 

Since the election of David Cameron in 2005 there have been no big outside winners. The next contest, in 2016, was fought in completely different conditions. Rather than a leisurely examination of candidates from the opposition benches, the Conservative Party had to find a leader as the pound crashed and the country came to grips with the aftermath of the Brexit vote. Boris Johnson was the slight favourite, having masterminded the Leave campaign and was installed the 8/11 favourite with Theresa May second (7/4). 

After several key allies abandoned him, Johnson’s campaign collapsed. May’s eventual victory came as little surprise. Johnson’s decision to pull out would again give weight to the argument that front-runners rarely win the contest. He would, however, rectify this in 2019 when he emerged as the 1/5 favourite to beat Jeremy Hunt (7/1), Rory Stewart (16/1) and Sajid Javid (25/1) and did so with little resistance within the party.

As the party now seeks to find its fourth leader in just seven years, eyes will inevitably be drawn to the long list of candidates to see whether there can be a shock victory. For the first time in a generation there is no clear front-runner, which makes for a volatile and unpredictable contest. Can a Steve Baker, Suella Braverman or Kemi Badenoch confound the bookmakers and win as outsiders? History shows us that for all the talk of “dark horse” winners, candidates are usually established within the party before the campaign has begun. 

Instead, candidates such as Ben Wallace, Tom Tugendhat and Penny Mourdant are strongly fancied and will be scrutinised like never before. One person who has already felt the impact of being the front-runner is Rishi Sunak. At the 2019 election, when he was thrust into the media spotlight via the leaders debate, he still had a 100/1 chance to become the Prime Minister. He was such an unknown that some bookmakers even spelt his name wrong on their websites. All of that changed when he became the Covid Chancellor, responsible for populist policies such as “Eat out to Help out” and the furlough scheme. But after the controversy of his wife’s non-dom status and the spiralling cost of living crisis, his odds have fallen. He now enters this race without the pressure of favouritism and it remains to be seen whether that may actually help him turn those previous long odds into cold hard winnings for his backers.