David Cameron is a big international figure but what will he do as UK foreign secretary?

When Margaret Thatcher appointed Lord Carrington, the last Conservative foreign secretary based in the House of Lords, she said she had done so because he only had to walk into a room to establish his natural authority.

Although Carrington admired her sense of duty, the compliment was not completely returned. He once confided: “I think she had hardly been outside the country. From my point of view this was a considerable advantage for she could hardly contradict me when I told her where Rhodesia was.”

He also occasionally chided his prime minister in meetings with visiting presidents, passing her notes: “He has come five hundred miles. Don’t you think you should let him say something?” There was little doubt that Carrington was the dominant figure when it came to the broad sweep of foreign policy, if not relations with Europe.

There is a danger that Lord Cameron, with six years’ experience as prime minister and umpteen world summits under his belt, as opposed to Rishi Sunak’s single year, will be tempted not only to dominate foreign policy but to stray out of his lane and give very broad advice to his boss.

But with only a year to go till the next election, and two of the biggest foreign policy crises to face the UK since the Iraq war, Sunak will hope that Cameron’s major contribution will be to bring a Carrington-style air of stability and authority to the UK’s contribution to foreign policy.

The perception overseas has been that Britain has been a country at best suffering strategic drift, and at worst on the verge of a nervous political breakdown. Only the contribution in Ukraine – playing to British security and defence strengths – and the UK’s intangible soft power have prevented decline turning into something worse.

Cameron, by being a big figure, can change that. But it contains risks for Sunak. At a moment of great geopolitical consequence, he is relinquishing responsibility for foreign policy to Cameron – just as Tony Blair largely relinquished domestic economic policy to Gordon Brown.

Although some of the big global players of Cameron’s era have left the stage – Angela Merkel, Barack Obama, Nicolas Sarkozy – many others are still around: Donald Tusk, Mark Rutte, Vladimir Putin, Benjamin Netanyahu, King Abdullah of Jordan, Abdel Fattah el-Sisi, Xi Jinping, Cyril Ramaphosa and Narendra Modi.

David Cameron with Vladimir Putin after a meeting in the Black Sea resort of Sochi, Russia, in May 2013: they had been speaking about a political solution to end violence in Syria. Photograph: Sergei Karpukhin/AP

If the personalities are familiar, the issues are not. For instance, Cameron worked very hard in the opening years of his premiership, like Tony Blair, to form a strong leadership with Putin – even proposing the Russian gas pipeline Nord Stream could extend to the UK.

But the courtship fell apart over Russia’s support for President Bashar al-Assad in Syria. Cameron was initially a great supporter of the Syrian democratic revolution, even if he would admit in private that the Free Syrian Army was neither free, Syrian nor an army. His support for the revolution pitted him against Putin permanently.

Yet when he needed MPs’ support in 2013 to punish Assad and, by extension, Putin, for the use of chemical weapons, he was abandoned. The legacy of Iraq hung over Britain and the public’s willingness to intervene militarily, he concluded.

So given that chastening experience, Cameron will be content with the current balance of the UK policy on Ukraine: resolute against Russia and against direct UK intervention. Instead, he will be thinking how to rekindle the public’s enthusiasm for the Ukrainian cause, and Ukraine’s aspiration to join the EU. Stand by for a lot of “Fire up the Quattro” rhetoric, especially when he meets European prevarication over arms supplies. He is after all a strong Nato man, the architect of the 2014 summit that led member states to commit to spending reaching 2% of GDP.

On the second great foreign policy crisis – the Palestinian issue – Cameron is an enthusiast for the state of Israel, but capable of telling Israel that Gaza as an open-air prison is in no one’s interest. He tried in a speech to the Knesset in 2014 to avoid the weeds of an eventual peace deal and instead give Israel a vision of the benefits of peace and compromise. He will be a friend of Israel, but a more critical friend than his predecessor, who largely went through the motions of supporting a two-state solution.

Knowing Cameron, he will also be asking his former foreign policy adviser in No 10 John Casson how Britain can insert itself into the debate about what happens in Gaza on the day after the defeat of Hamas. Casson was recently deeply critical about the banality of the British debate.

Cameron is also likely to echo Joe Biden in suggesting to Netanyahu that lessons have to be learned from the west’s flawed response to 9-11. One of the leitmotifs of Cameron’s premiership was the threat of radicalised terrorists returning from Syria, and the sources of extremism. Given that experience, he will have to make a judgment whether a purely military solution in Gaza is a chimera, and how to tell the Israelis as much. Many foreign policy analysts think the west has not yet understood the whirlwind it will soon reap for its perceived double standards over Ukraine and Israel.

David Cameron enjoys a pint in a Buckinghamshire pub with the Chinese president, Xi Jinping, during the latter’s visit to the UK in October 2015. Photograph: Kirsty Wigglesworth/AP

His friends say he knows he is braced for criticism for his business dealings with China, as he has already endured from the intelligence and security committee. China-sceptic Tory backbenchers hate his enthusiastic embrace as prime minister of the golden era in relations with China.

But his friends say since then, human rights issues in Xinjiang and the suppression of the Hong Kong democracy protests have changed the facts. In reality, British policy in China – largely led by Washington – has been in a state of permanent flux, and is leaning away from confrontation and back to engagement, Cameron’s natural stance.

If he has the headspace, Cameron may also return to two enthusiasms: development and fighting corruption. He has a great ally in the development minister, Andrew Mitchell, and will take a personal interest in a development white paper due shortly. He sees UK aid as a reason to be patriotic, and out of office took on a job updating the UN sustainable development goals.

As chair of the G8 in 2013, he started asking British overseas territories some hard questions about hiding economic crime. Again it was an issue that he pursued with Transparency International out of office.

One flaw Cameron will have to watch is arrogance. He regards himself as a natural leader, but he made mistakes ranging from the aberration of Libya to the massive unforced error of Brexit. All political careers end in failure, but few get resurrected after such a complete one as his.