Every prime minister comes to a point in the job after which everything seems to start going downhill — the original lustre fades, government loses vitality and purpose, hope is replaced by cynicism.

Sometimes this witching hour appears early on. Edward Heath had been prime minister for scarcely one year when the impending bankruptcy of industrial giant Rolls-Royce in 1971 forced him to nationalise the firm and abandon the Tories’ free market industrial strategy.

Sometimes, a PM holds out much longer. For example, Margaret Thatcher had been in No 10 for ten years when her daring plan to introduce the poll tax hit the buffers, paving the way for her political assassination.

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'I believe that future historians will identify 2016 as the year David Cameron lost his way. Even physically, he looks different: increasingly tired and jowelly', writes Peter Oborne

Often, the change in fortunes is connected to a single calamitous event.

John Major, for instance, never overcame the debacle of Britain’s humiliating eviction from the Exchange Rate Mechanism (a precursor to the euro, designed to bring monetary stability to European currencies) on Black Wednesday in September 1992.

For his part, Tony Blair survived as PM for another four years after the Iraq invasion of 2003 but was never trusted again because it was proved he took Britain to war on a lie.

I believe that future historians will identify 2016 as the year David Cameron lost his way. Even physically, he looks different: increasingly tired and jowelly. He has lost much of his early grace and charm, becoming petulant and tetchy.

This was encapsulated in an incident two weeks ago when he lost his temper with journalists on a trip to Washington.

Asked if he had taken his eye off the ball because of the EU referendum, he snapped: ‘I don’t accept the premise of your question for one moment.’ Then, bizarrely, he accused reporters of ‘setting each other’s hair on fire’.

This is a very bad sign, mainly because it shows that he is losing the self-discipline and poise that used to be among his hallmarks.

Certainly, major problems are mounting. There have been the Government’s humbling U-turn over planned cuts to disability benefits, the steel crisis, the Tory civil war over whether to remain in the EU and a personal crisis for Cameron over allegations of hypocrisy after having benefited financially from a tax-avoiding offshore fund run by his stockbroker father.

Cameron has compounded this catalogue of troubles by making silly mistakes.

Take, for example, his Government’s handling of the steel crisis, which risks leading to the final collapse of the industry in the UK, with an estimated 40,000 jobs hanging in the balance.

It had been obvious for some time that Tata was considering closing the steel plant in Port Talbot.

Earlier in his premiership, Cameron would have been alert to the threat and grabbed the initiative. But now, it seems, he was taken by surprise.

Similarly, the damaging political storm over the £19,000 profit (plus any dividends) he made from his father’s investment trust held in Panama is another case in point.

I do not believe he has done anything seriously wrong. He has committed no crime. He seems to have paid all relevant British taxes and the shares were sold before he became prime minister.

Yet his entanglement in the so-called ‘Panama Papers’ scandal has been handled with breathtaking incompetence. It took Cameron four bungled and disingenuous denials before the truth was forcibly extracted. This made the PM appear shifty and even deceitful.

Cameron has compounded a catalogue of troubles by making silly mistakes, writes Peter Oborne

The episode has reinforced the idea that Cameron’s Conservative Party is concerned with looking after the interests of only the rich and famous. As I said, it is the cumulative effect of these problems that seems so injurious.

Most serious is the fact that June’s EU referendum has caused one of the most damaging splits in the 200-year history of the Tory Party. Cameron’s handling of the campaign has been atrocious from the start.

Although he made a cast‑iron promise to the British people that he would obtain ‘fundamental’ political reforms and a ‘better deal’ for the UK from Brussels, he reneged on that pledge.

Indeed, I believe that he never put his heart into the negotiations and this showed. Despite endless PR spin from Downing Street, the PM placed himself at the mercy of his European counterparts.

Having failed dismally to achieve any substantial reforms, he has since been arrogantly partisan in his conduct of the debate. As a result, government has become paralysed and his party poisoned by feuds.

SILENT FARAGE Nigel Farage is a notorious loudmouth who will wade into any controversy. So why the relative silence from the Ukip leader as David Cameron is forced to squirm for having benefited from a Panama-based offshore trust? Could it possibly be that many of Farage’s backers are hedge fund managers and other members of the super-rich who also like to keep their extensive assets offshore? Advertisement

It is a sign of the depth of the crisis that this week witnessed a very unusual intervention from one of Cameron’s most fervently loyal friends, the Conservative journalist Bruce Anderson.

The pair have been close for many years and Anderson has long been ridiculed for fawning — if not sycophantic — praise for the PM and his Downing Street machine.

Yet, in a lacerating article for the Conservative think-tank Capx, he excoriated the PM’s No 10 inner circle.

First, he castigated Cameron’s director of communications, the former BBC executive Craig Oliver, describing him witheringly as ‘a largely unknown figure with a lot to be unknown about.’

He continued: ‘In terms of pounds per unit of output, he is one of the most overpaid officials in the history of modern government.’

I know Mr Oliver a little. If anything, I think Anderson was being too kind.

More importantly, Anderson then dealt with Cameron’s very close colleague, Tory Party chairman Lord Feldman. The two men met at Oxford University where they were tennis partners.

Anderson thundered: ‘When it comes to politics, he [Feldman] neither knows nor cares.’

He called for the unelected crony to be ‘supplemented’ (i.e. replaced) ‘with a powerful figure who could both go on the [Radio Four] Today programme and enthuse the party in the country’.

I hope the Prime Minister has the wisdom to take this well-meant advice. If not, I fear not just for his future but also for the future prospects of the Tory Party.

The ineluctable fact is that David Cameron has lost his way.

The lesson of history tells us that he will struggle to recover his energy and verve after the last few bruising weeks.

But it is imperative that he does. Otherwise his legacy will be greater mutiny in the Tory Party, a severely tarnished personal reputation and, more importantly, a country left to drift rudderless.

Steel and another Osborne crony on the make

Not long ago, Business Secretary Sajid Javid was widely seen as the next Tory superstar. Thanks to powerful allies and influential supporters in the Press, he could do no wrong.

However, the steel crisis has found him out. It is utterly unforgivable that he ignored the warning signs about difficulties at Port Talbot and did not bother to go to India to meet the plant’s bosses as they made the decision whether to sell its UK steel assets.

In addition, morale at Javid’s departmental headquarters is at rock bottom. So, what has gone wrong?

'I believe that Javid is one of many ministers who have been promoted beyond their natural ability, thanks to the patronage of Chancellor George Osborne' Peter Oborne writes

I believe that Javid is one of many ministers who have been promoted beyond their natural ability, thanks to the patronage of Chancellor George Osborne.

Other examples are Skills Minister Matthew Hancock and Energy Secretary Amber Rudd, whose absurd scaremongering about how people’s energy bills would rise if we leave the EU were ripped to shreds by the BBC’s Justin Webb on the Today programme recently. The truth is that such people are being overpromoted simply to bolster Osborne’s support base.

This, sadly, is yet another example of how the ever-ambitious Chancellor is a liability to both the Government and the country as a whole.