SIMON WALTERS: Be wise, Boris… and don’t repeat Margaret Thatcher’s mistake 

Personal and political tensions with their Downing Street neighbours played a large part in the demise of the two most powerful Prime Ministers of the past 50 years.

Tony Blair was undermined from his first day in office by a bitter Gordon Brown, who never even let Blair see his Budget speeches in advance.

The downfall of Mrs Thatcher, meanwhile, was triggered by her former Chancellor Geoffrey Howe, who avenged years of being treated with contempt by the Iron Lady with a devastating Commons attack on her.

By contrast, Boris Johnson’s relations with Rishi Sunak since he promoted him from nowhere to be Chancellor last year have been surprisingly friendly… until now.

Boris Johnson’s relations with Rishi Sunak since he promoted him from nowhere to be Chancellor last year have been surprisingly friendly… until now

The Prime Minister is said to have been so enraged by a leaked letter from Sunak – in which the Chancellor demanded Covid travel curbs be eased to save the economy and summer holidays – that he threatened to demote him to Health Secretary.

Boris, it is also claimed, is attracted by the idea of appointing Liz Truss, currently the International Trade Secretary and a rising star in the Tory Party, as Britain’s first woman Chancellor.

Boris’s fury is taking place in the context of a poll that shows an astounding 36-point drop in his once rock-solid ratings among Tory voters.

Meanwhile, Sunak’s popularity in the same survey by the influential ConservativeHome website remains sky-high.

Nobody seriously believes that Sunak is out to topple Johnson. And the Chancellor is well aware that when he sends out tax bills to pay for the generous economic policies deployed during the pandemic – he could go quickly from hero to villain.

Having said that, it is impossible not to be impressed by the rise of Sunak, who was a political unknown before he took over the Treasury last February.

The downfall of Mrs Thatcher, meanwhile, was triggered by her former Chancellor Geoffrey Howe, who avenged years of being treated with contempt by the Iron Lady with a devastating Commons attack on her 

His performance as Chancellor has been as sharp as his ankle-skimming suits, and he has yet to put a foot wrong.

Johnson, however, committed another gaffe only last week when he made an off-colour joke about Mrs Thatcher’s ruthless closure of the coal mines during the 1980s: comments said to have offended voters in the Tories’ ‘Red Wall’ of northern seats.

Though Johnson and Sunak initially formed a rock-solid alliance to deal with the pandemic, fault lines have emerged between them in recent weeks – from divisions over Boris’s new ‘Royal Yacht’ plan to his ‘levelling-up’ agenda.

It all costs money, and Sunak – who did book-keeping for his mother’s pharmacy as a teenager – has his hands firmly on the purse strings. The disagreements have highlighted the stark differences between the two in both style and substance.

‘Boris announces grand projects out of the blue without thinking how to pay for them,’ said one Conservative adviser.

‘He wouldn’t have a clue how to read a balance sheet. Rishi doesn’t have Boris’s common touch but he can spot a few missing pence.’

Their relationship is so closely watched that even the Sunaks’ acquisition last month of a labrador puppy, Nova, was seen by cynics as an attempt to upstage Mr Johnson and wife Carrie’s beloved Jack Russell-cross, Dilyn.

Let’s be clear: having won a landslide election victory less than two years ago and following the success of the Covid vaccine roll-out – all helped by a weak and divided opposition Labour party – it is surely too early to be writing Mr Johnson’s political obituary. However, for all his unique talents, the Prime Minister’s friends say he has never been interested, as Thatcher and Blair were, in spending a decade at No10.

Tony Blair was undermined from his first day in office by a bitter Gordon Brown, who never even let Blair see his Budget speeches in advance 

He intends to return to his main, highly-lucrative passion: writing.

And unlike Thatcher and Blair at the same stage of their Prime Ministerial careers, having brought about and delivered Brexit, Johnson’s place in the history books is guaranteed.

The all-encompassing nature of the pandemic has made it difficult for him to add a second chapter to his tenure after ‘getting Brexit done’.

But in my view, he is more likely to achieve that by working together with the loyal and even-tempered Sunak, rather than by fulminating wildly in private about him.

If Mr Johnson is seriously considering carrying out his reported threat to demote Sunak to Health Secretary, he might care to reflect on Mrs Thatcher’s fate after she dished out a similar unmerited punishment to Howe, who had been her first Chancellor.

Irked chiefly by his opposition to her anti-European views, and emboldened by a landslide election victory two years earlier, she humiliatingly gave Howe, then the Foreign Secretary, the Cabinet dogsbody job of Commons Leader in 1989.

But if Thatcher thought she had put him in his place, just 16 months later, the mild-mannered Howe moved against her. She was gone in three weeks.