This is an unedited version of my Sunday Telegraph column.

Just as the last four Tory prime ministers have been defenestrated by the issue of Europe, the next one will almost certainly be defined by it.

It will also dominate the imminent leadership campaign, as each candidate will be expected to come up with their own well worked out plan for how they intend to extricate us from the EU by Halloween.

Candidates who merely parrot maxims about ‘delivering on the referendum’ or fail to provide any detail of their approach should immediately be viewed with great suspicion. Matt Hancock fell victim to this on the Today Programme yesterday, where he went round and round in circles, uttering soundbite after meaningless soundbite about “uniting the country” and “delivering Brexit”. He said nothing that Theresa May couldn’t have said, and therein lies the rub. All the leadership contenders who served in Theresa May’s cabinet until the bitter end have to answer two question: why did you sign up to her policy, which was never going to work, and aren’t you just ‘Continuity May’?

Boris Johnson, in a speech in Switzerland on Friday, declared triumphantly “We will leave the EU on October 31 – deal or no deal.” The trouble is, given what’s happened over the last three years, no one believes any politician who utters such ‘certainties’. The very appealing and simplistic message that Nigel Farage has transmitted during the European election campaign does not necessarily translate to a Tory leadership contest – not to the parliamentary stages anyway.

Their fellow MPs are going to expect well thought out negotiating plans from the candidates, rather than bluster about leaving with no deal. If candidates are being brave they will tell an unpalatable truth, and that is that it will take far longer to sort things out than 31 October. The European Commission hardly functions in August and it’s already a lame duck. A new Commission won’t be appointed until 1 November. The brave candidate will propose extending Article 50 by another twelve months to enable not only a new deal to be negotiated, but a proper no deal planning process to be embarked upon. Each candidate must explain what a so-called ‘managed no deal’ would look like.

This is, in part, why it is vital that there is no ‘coronation’ this time. It may well be that one of the final two candidates has an MP vote tally which dwarfs the second one. So what. All candidates should pledge at the outset that they will stick the course come what may. The winning candidate has to be tested to destruction and a four week long campaign in the country with up to a dozen regional hustings, TV and radio debates and interviews, will enable not just Conservative Party members but also the country to assess the strengths and weaknesses of our future prime minister. There will be many who say ‘oh just get on with it’ and ‘for the sake of country’ the second candidate should drop out because the country needs certainty, and quickly. Those siren voices should be ignored. If Theresa May had had to endure that process in 2016, maybe the weaknesses that soon became all too apparent would have emerged and something could have been done about them.

Self-knowledge is a wonderful thing, but it is an asset which few politicians possess. If they did, at least half the likely candidates rumoured to be wanting to take part in this leadership election wouldn’t be standing. Ego and ambition are triumphing over reality. One or two candidates are standing merely to put a marker down for next time, or in some naïve way try to bag a bigger cabinet job than they otherwise might have been given. They will fall by the wayside very quickly, and humiliatingly in some cases. If you only get five or ten first round votes, why bother to stand in the first place? All you achieve is getting a reputation for misjudgement and desperation.

In terms of a narrative and policy proposals Dominic Raab is ahead of the pack. He’s also stolen a march on his rivals with a well-developed campaign infrastructure, including two of the best media operators in Tory circles, James Starkie and Paul Stephenson. He’s also got some interesting parliamentary backers from across the party, not just the right, which include Maria Miller, Shailesh Vara and Nadhim Zahawi.

However, the pro Brexit ERG vote is inevitably going to be fractured in the initial parliamentary rounds, with Andrea Leadsom, Esther McVey, Steve Baker and Sir Graham Brady all vying for votes with Raab and Boris Johnson. Whatever happened to the plan to have one candidate?

Jeremy Hunt and Sajid Javid have both been very keen to burnish their Brexity credentials in recent months and the key to their chances of success will be to what extent Brexit supporting Tory MPs will buy it. Judging by their declared supporters so far, not so much.

Michael Gove is the one candidate who could unite both wings of the party, but the trust issue is still a worry for many. He is not to be underestimated, both in organisation and ability to enthuse.

Of the less known candidates, one of them is likely to emerge as a dark horse. If I had to put my money where my keyboard is, I’d identify Penny Mordaunt, the new Defence Secretary. She is unique in the field in that she’s liked by everyone in the parliamentary party, and that’s not a bad place to start from. She’s one to watch, even if at this stage it’s difficult to analyse where her support will come from.

A lot has changed in the last few weeks. A month ago, I’d have laid bets that Boris Johnson wouldn’t get into to the top two. I am now utterly convinced that he will, assuming he manages to broaden his support from all parts of the party. He will, in many ways, rightly portray himself as the candidate with electoral stardust – the only one would can take the fight to Labour and beat them. If he gets into the final two, he will be home and hosed unless something dramatic happens in the meantime. He will, however, have every other candidate trying to bring him down. Journalists will be scouring every closet in the land for more skeletons. Every interviewer will be desperate to land the killer blow that knocks him out of the race. So far Boris’s Teflon like exterior has served him well, but the question is, can his luck continue? We are about to find out.