“LET’S face it, the simple fact is that you’re a habitual liar, aren’t you Prime Minister?”

A stony silence.

“You said your party has a zero-tolerance approach to Islamophobia, so what action should be taken against you for using the term ‘letterbox’ to describe Muslim women who wear a burqa?”

More silence.

“Will you tell voters the truth about your relationship with businesswoman Jennifer Arcuri and why you didn’t declare a personal interest when you were London Mayor?”

Yet more silence.

If Boris Johnson really does fail to appear for a grilling by Andrew Neil, the BBC should just go ahead with a half-hour prime-time programme where the Prime Minister is empty chaired.

Mr Neil could read out the questions he would have asked anyway, making for compelling viewing. But perhaps even that would be a risk that Dominic Cummings and Tory advisers would be willing to take. After all, those who have agreed to an Andrew Neil interview in this election campaign have found it an unforgiving experience.

First up was Nicola Sturgeon.

The First Minister is an accomplished media performer – easily the most competent politician in front of a camera in Scotland, and surely in the top ten across the UK.

Her interview wasn’t quite the car crash that social media would perhaps suggest, but it was certainly a deeply uncomfortable 30 minutes.

Her wild assertions about how easily an independent Scotland could stroll into the EU were ruthlessly exposed, and she may come to regret describing the SNP’s currency tribulations as a ‘journey’.

The 45-second-long list of problems facing the NHS under the Nationalists also deserved the million-plus audience it has since received online. Yet at times the First Minister held her own and, realistically, her performance is unlikely to cost the SNP many votes.

However, it might help some Labour left-wingers in England understand why their Scottish colleagues get so angry when they describe Ms Sturgeon as a comrade.

Predictably, the Labour leader, Jeremy Corbyn, fared far worse in his own interview. Thoroughly displeased at being there, he repeatedly struggled to explain how he would pay for his manifesto promises.

Then, with voters screaming ‘just apologise’ at their TV sets, he refused four times to say sorry for the anti-semitism shaming his leadership.

If heads were in their hands at Labour HQ, the verdict in Tory HQ will have been ‘well… sod that’.

The Andrew Neil interviews have given voters some food for thought, as these set-piece TV events should.

The ITV head-to-head between Mr Johnson and Mr Corbyn has been the only major let-down so far, with a bizarre format which gave neither politician enough time to answer the questions. On this occasion, the victors were those not invited – Jo Swinson and Nicola Sturgeon. With hindsight, perhaps they should have saved their parties from the huge legal bill of trying to get on the line-up.

In contrast, the winners in Thursday night’s climate change debate were those who did appear, with Boris Johnson and Nigel Farage reduced to ice sculptures for not showing up.

When it comes to how much impact these debates have on the final election result, the jury is out – Cleggmania in 2010 didn’t really translate to Commons seats.

But Electoral Reform Society research has found that 56 per cent of people believe debates are important, and a third say they're key to helping them decide how to vote.

They want to see points put across clearly, factual evidence for claims, and a debate that engages the audience watching at home. And as well as being watched by millions, they certainly set the campaign narrative.

In 2014, Alistair Darling bested Alex Salmond in the first TV debate of the independence campaign. If you can’t remember it, Mr Salmond decided to ask questions about alien attacks, while Mr Darling pointed out that an eight-year-old could name their country’s capital, flag and currency, but Mr Salmond couldn’t say what currency an independent Scotland would use.

In the 2017 election campaign, I was involved behind-the-scenes in the Scottish TV debates. The amount of preparation work was immense. Days of going over attack lines, defence lines, introductory remarks, key messages, second-guessing opponents, and the occasional bit of role-play.

Spin doctors had their own role to play on the night as well. The first debate on the BBC involved a nurse telling Ms Sturgeon to her face that NHS staff were having to use foodbanks. While journalists in the spin room tried to file their copy, political advisers interrupted them, talking up their own employer to some extent, but mainly talking down the rest of the line-up.

For the SNP, this backfired when the message was spread that the nurse’s husband was a Tory councillor. It categorically wasn’t true.

However, the Nationalists had a better night of it at the STV debate. Unusually, the broadcaster decided not to provide individual green rooms for the politicians, so they all had to share the same space for a long time before taking to the stage.

Willie Rennie and Ruth Davidson dealt with this through humour, cracking jokes to demonstrate confidence. Kez Dugdale, who I was working for, focused on her notes. Nicola Sturgeon kept herself to herself. She had something up her sleeve.

In the debate, she claimed that Kez once told her in a private conversation in the aftermath of Brexit that Labour might rethink its opposition to an independence referendum – something she strongly denied. But having run a campaign focused on opposition to independence, this was a ‘gotcha’ moment. It was, comfortably, the toughest moment of the campaign.

So I wish my successors at Scottish Labour, and at all parties, every good fortune for the coming days.

This campaign still has nearly a fortnight to run. The Scottish TV debates have yet to be broadcast, there is another Prime Ministerial head-to-head to come, and it remains to be seen if Boris Johnson will sit down with Andrew Neil.

There are a lot of nervous politicians, and a lot of nervous spin doctors. They have a right to be nervous, because the voters deserve more honest answers.