BACK in the old days, when life in Britain was one long Hovis advert (youngsters: see YouTube), purdah in politics was a very big deal.

The word comes from the Urdu for “curtains”. As soon as an election is called a metaphorical curtain is meant to be drawn between Whitehall and politics. Behind the curtain the Civil Service, having gone into purdah, does nothing that could benefit any of those grubby politicians “out there” fighting for seats. It is a bit like self-isolation, but without the watching of Homes Under the Hammer (although who is to say that does not go on among the Sir Humphrys ...)

Purdah applies to Budgets as well. The Treasury, fearing that a leak could influence markets or give an advantage to certain businesses, is meant to go into lockdown before the statement.

Woe betide anyone who breaks Budget purdah. Hugh Dalton, then Chancellor of the Exchequer, had to resign on Budget day in 1947 for divulging details to a reporter before addressing the Commons. John Major called the police after his government’s 1996 Budget was leaked to the Daily Mirror (the then editor, one Piers Morgan, did not publish).

These days, we are all so much more relaxed and grown up – so much so that the Chancellor, Rishi Sunak, can spend the Sunday before the Budget touring the politics shows and giving an interview to a newspaper (Sunday Telegraph: “I will not let virus cripple the economy” says Chancellor).

No hiding away by this Chancellor. Not, it should be stressed, that he gave anything away. Mr Sunak was careful to pepper his interviews with The Andrew Marr Show and Sky News’s Ridge on Sunday with phrases such as, “You’ll have to wait for Wednesday”; and that old standby, “I can’t comment on the Budget in advance”.

He is only three weeks in the job and just 39-years-old, but in the art of appearing to say something while in reality giving nothing away, Mr Sunak proved himself a master already.

Why did he bother appearing at all, you might wonder. Well, for one, this is the Chancellor’s time in the spotlight and like any ambitious politician he is going to make the most of it. Secondly, his predecessor resigned due to Number 10 trying to mount a takeover of the Treasury. This was Mr Sunak’s chance to show he is his own man.

There was another reason of course: the coronavirus, which is having as big an impact on his Budget as it is on everything else. With share prices tumbling and fear rising among businesses and employees, the Chancellor had to get out there and sell the message that everything was going to be okay. “We will get through it,” he told Marr, adding that he could say “absolutely, categorically” that the NHS would get whatever it needs “to get us through this crisis”.

As he spoke, there were reports of supermarkets rationing purchases of toilet rolls and hand sanitising gel. During the paper review on Marr, everyone agreed that the media had a tricky job trying to strike a balance between highlighting the seriousness of the situation while not being alarmist.

As if to underline the extent of the crisis, Marr blurted: “I’ve just cancelled an art exhibition of my paintings!” I expect that news will be on every front page today. Or perhaps not.

But the presence of Mr Sunak alone was not enough to bring home the “keep calm and carry on” message from government. For that level of reassurance the big gun had to be wheeled out.

No, not the Prime Minister. It was a Sunday. He does not do Sundays. Nor was it a senior health official, though every television show and radio programme had one of them. No. To paraphrase Samuel L Jackson’s character in the movie Jackie Brown, when you absolutely, positively, have to quietly reassure everyone in the room, accept no substitutes for the First Minister of Scotland, Nicola Sturgeon.

Beamed live from what looked like her home in Glasgow (same Val McDermid and Ian Rankin-filled bookshelves behind her), she appeared first on Ridge on Sunday. Later in the morning, moving to the conservatory for a change of scene, she popped up on Sunday Politics Scotland for an interview with Gordon Brewer.

Whatever the backdrop, her message was the same: we’re doing everything we can, and taking all the expert advice available, to keep people safe and treat them if they fall ill.

She was calm and measured, talking down the scarier scenarios, concentrating on what was being done and, crucially, how the public could help by the simple act of washing our hands regularly.

The FM was, in effect, doing Mr Johnson’s job for him. Not that she said as much, or hinted anything of the kind.

Indeed, she stressed that everyone was working well together across the UK and that such a crisis should not be used for political gain. But the point was made: she was there, up early on a Sunday, exuding reassurance, and Mr Johnson was not. Enough said.