I backed Remain. But I believe Boris Johnson should be the next Conservative leader

I supported the campaign for a vote to stay in the European Union because I believed that the UK would have been stronger, safer and better off in. David Cameron is someone I admire, like and am loyal to. So I felt bewildered and upset on Friday morning, when it became clear that we would be leaving the EU and the Prime Minister then announced his resignation.

But whenever I felt like giving in to despair, or the desire to storm off and sulk, I would hear the voice of my late father in my ear. “Come on, Nicholas,” he would say – never having liked the name Nick – “You are in public service. And the people you serve have made a decision. This isn’t a time to be petulant. You need to listen to them carefully, and to do what you can to make a success of things.”

As Conservatives, we now have to make a very hard decision. We need to choose the best person to lead our party, and our country, and implement our withdrawal from the European Union, while keeping the United Kingdom together, and governing fairly and effectively in the interests of everyone in society.

In making our choice we must resist the natural urge to give into emotional spasm. We must choose calmly, with our eyes open and focused firmly on the future of our country and the best interests of its people.

Our next Prime Minister must fulfil a number of important conditions if she or he is to have any chance of succeeding in the crucial months and years following the referendum.

First, although I campaigned hard for a Remain vote and greatly admire many of the party’s leading lights who did so with me, I cannot escape the conclusion that our next Prime Minister needs to be someone who supported the idea of leaving the EU.

It would be hugely damaging to an already fragile sense of trust in our political system if the 52% of voters and 58% of Conservative supporters who backed Brexit were told that this momentous decision would be taken forward by someone who didn’t believe in it.

It will be essential for the new cabinet to bring together talents from across the party, and include people who passionately supported our continued membership of the EU.

But the Prime Minister needs to be someone who can stand up and say that they wholeheartedly support what will be the defining mission of the new government.

Whoever takes over from Cameron will be pitched straight into one of the most demanding jobs in the world, at a pivotal moment in our nation’s history, and will face massive challenges.

So we do not have the luxury, as we had in opposition, of choosing someone young, fresh and inexperienced. This really is no time for a novice. We need to elect someone who has deep experience of leadership, and can cope with the relentless pressure and exposure of a top-flight political job.

The intemperate and often unpleasant nature of the referendum campaign has highlighted divisions in society, between classes, generations and different parts of the country. 48% of the country voted to stay in the European Union and many of them are feeling bruised, frightened and rejected.

If we are not very careful, the process of implementing the people’s decision will exacerbate those divisions and risk splitting the country apart. So we need to elect someone who is a natural unifier, and consensus builder, a fully paid-up member of the human race, who doesn’t just spout the rhetoric of One Nation, but lives and breathes an approach to politics that is warm, generous, open and inclusive.

Finally, as members of the most successful political party anywhere in the world, we must not neglect the important matter of winning elections. In time, our new leader may feel the need to secure a renewed mandate from the British people and return to Parliament with a clear majority committed to implementing the people’s decision.

Yesterday’s developments suggest we could face a new and more credible Labour leader when this happens. So we must choose a standard-bearer who can appeal to voters of all ages, races, backgrounds in every part of the count – someone who can reach the parts of Britain that other Conservatives find hard to reach.

It is these four conditions that have led me to conclude that we should elect Boris Johnson as our next leader and Prime Minister. I have worked closely with Johnson as his chief of staff when he was first elected Mayor of London.

We have had well-advertised differences in the past. But he is a modern, liberal Tory, who won two elections in a city that is naturally Labour, who has grown immensely in stature and maturity in his eight years as Mayor, and who will lead the country with the same humanity and sense of fairness that he brought to the leadership of our capital city.

Many of my closest friends in politics, people who fought alongside me in successive battles to modernise our party, and win back the trust of the British people, people who shared my feelings of dismay at the result of the referendum and the resignation of a leader we believed in, will struggle with the choice I am recommending.

I understand completely where they are coming from. But I am going to spend the next three months doing my best to explain to them, as the spirit of my late father explained to me, why the national interest must come first and why, in the national interest, we must elect Johnson.