Dear Boris, here’s how to succeed in your desperately difficult new job

To avoid a shortlived premiership, the next PM will have to embrace his disaffected colleagues

Dear Boris, The entire Conservative Party expects you to become prime minister tomorrow. Congratulations – it’s not every day that a fellow Daily Telegraph columnist is elevated to this position. You carry the hopes, even of those of us who didn’t vote for you, that you will defy the odds to keep both country and party intact and successful. But you face the most immediately daunting challenge on entering No 10 since Churchill, who you have studied so attentively, stepped over its threshold in 1940.

None of us who have preceded you as Tory leader can claim perfect wisdom since we have all made mistakes. On the basis of observing several prime ministers at close quarters, however, here are some thoughts about what to do.

It can easily become a lonely job, and there is an opportunity at the outset to prevent that. If you treat your senior Cabinet colleagues with respect and invite them in constantly to your inner counsels, they will respond with loyalty, commitment and developing a common bond. Most prime ministers neglect to do this, and end up

hunkered down with advisers in a tightening circle of paranoia.

The entirely unsurprising seizure of a British-flagged tanker by Iran is a sharp reminder that national security must be of paramount concern. An incoming PM needs to become steeped in such issues in the opening days, or will be vulnerable to being floored by a sudden and less predictable crisis. Even more alarming, the cohesion of Western foreign policy is slowly falling apart – relations with Iran, Turkey’s estrangement from Nato, and widely varying approaches to Chinese technology are all examples of this. A British leader needs to be part of binding the West together, or Brexit will one day be seen as the prelude to a more catastrophic disintegration.

One of the main reasons you will have been chosen is that you did a remarkable thing: you were twice elected as a Conservative mayor of London. The philosophy you espoused then, as a fiscal conservative and social liberal, is the route to maintaining the Tories as a broadly based party of government. Fiscal conservatism means not rushing to spend money in the first few weeks, but using a spending review to keep a lid on hopes and a grip on ministers.

Social liberalism includes setting out a visionary immigration policy, showing proper control but welcoming the talented foreign student or desperate refugee. You can admire President Trump’s political skills, but it’s vital to avoid his current approach of seeking re-election by exacerbating division. Be the unifying, tolerant, open-minded figure you showed you were at City Hall. And never forget that you are leading a United Kingdom in danger of breaking up.

You will appoint, hopefully, some bright, new, energetic ministers. Set them to work on pro-enterprise ideas that will attract business to Britain. But you are also losing some excellent and highly experienced ministers, and here looms the first of twin and mortal dangers. The “do or die” approach to Brexit by October 31 is counterproductive, since it fails to frighten the EU but is driving some current Cabinet ministers into opposition inside the party. A government whose main policy is opposed by Philip Hammond, an accomplished Chancellor; David Gauke, an excellent Justice Secretary; and Rory Stewart, one of the best hopes for the future, is in nearterminal trouble from its first hour.

It will be worth keeping in personal contact with these and other disaffected colleagues, since it would be bad enough for a Tory government to be brought down by its own side but still more tragic if it happened because of misunderstanding. Similarly, do not underestimate the importance of meeting the EU leaders you believe will compromise with you face to face and genuinely knowing them. The digital world has not superseded the need for human contact and chemistry at the top of world affairs. You will be told that “Merkel will agree to this”, or “Macron will never allow that”, but, astonishing as it may be, you have to look into their eyes to know – just as Churchill did so often with Roosevelt.

This brings me to my main piece of advice: you will have to make up your own mind about your solution to Brexit, quite quickly, and based on your own contact with leading figures at home and abroad, because otherwise you will be buffeted between rival groups of your own advisers. Creative tension in government can be a good thing up to a point, but opposing approaches to the central issue within your own team are the other mortal threat to your premiership.

Such danger is already clear from your leadership campaign. You have consistently advocated an improved deal with the EU, but you have steadily made that pretty much impossible to obtain. When you ruled out changes to the Irish backstop last week and insisted that it must be removed altogether, you dismayed some of your advisers and delighted others. But the delighted group are those who believe that the EU will back away completely from the Withdrawal Agreement they spent two years negotiating, and go for a standstill period and a “light touch” trade deal instead. Unfortunately this is a fantasy, and always has been. Only you, as prime minister, will be able to ensure a cohesive strategy and bring it in line with reality, if it is not already too late to do so.

The wafer-thin margin of the Conservative and DUP majority in the Commons, and the opposition to your Brexit policy by a substantial number of Tories, means that unless you have a lot of Labour MPS up your sleeve you are only a few weeks from a fateful choice: becoming the second prime ministerial prisoner of this deadlocked parliament or seeking a new parliament. It is perfectly good to be mysterious about what you will do in this situation, as long as it is not a mystery to you. From day one, it would be wise to have the plan for a general election clear in your head.

Millions of people horrified by Corbyn want you to succeed. But unless your plan for Brexit is grounded in the reality of what this country faces, it will not work. And unless you lead with a broad, centre-right, unionist instinct, our party will not survive the trauma to come. Good luck, and please don’t muck it up.