Sir Alex Ferguson, Carol Vorderman, Lord Alan Sugar or Martin Lewis - who do you reckon should be the UK’s next prime minister?

That was one of the questions in a new study of voters that emerged over the weekend. Not just any survey, mind. This one was the main item on the BBC’s flagship politics show, Sunday with Laura Kuenssberg, and had extensive coverage on the corporation’s website over the weekend.

Lewis’s many admirers will not be surprised to learn the consumer champion and general good egg was the majority pick to be the best prime minister. But here is another query: what was the point in the question being posed at all?

Granted, the prime minister question was a bit of fun at the end of what was no doubt a long session. Mr Lewis will be relieved to hear that no one is expecting him to call the removals van today.

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It is still worth noting that the exercise took place at all. Like everyone else, television is gearing up for what could be a long general election campaign. This is not the first time, and it won’t be the last, that broadcasters try to liven up politics coverage with something different.

In the case of Kuenssberg’s show, a group of “nearly 50” people were brought together by More in Common. The research group describes itself as “a non-profit organization committed to advancing the common good of the societies in which we work”, and that it is “independent of partisan or political interests”. Founded after the murder of Jo Cox MP in 2016, it takes its name from her maiden speech in parliament where she said: “We are far more united and have far more in common than that which divides us.”

The sample was divided into six groups. These included loyal Labour voters, loyal Conservative voters, undecided voters, and first-time voters.

All the participants came from so-called “red wall” seats - former Labour strongholds in the north west of England that switched to the Conservatives in 2019. While constituencies were not specified, the list of red wall seats includes Bassetlaw, Bishop Auckland, Leigh (Andy Burnham’s former seat) and Sedgefield (Tony Blair’s old stomping ground) to name a few.

Viewers in Scotland would immediately have picked up a problem here - no Scotland. Despite Kuenssberg, herself a Scot, labelling the exercise “our Britain in a Room study”, I struggled to see its relevance to Scotland. There was no mention of the political landscape being different here. None of the participants had a Scottish accent. Scotland was simply missing.

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Given the participants were from the north west, people elsewhere in England and Wales might have felt similarly left out. Even the term “red wall” is regarded by many as simplistic.

Kuenssberg conceded that this was not a “scientific” report and was instead a “snapshot” that took in the views of a range of voters. Indeed, so keen were the organisers to have a representative spread of voters they even included those intending to vote for Nigel Farage’s Reform UK. Good to see the BBC once again giving the omnipresent Mr Farage a seat at the table.

Sure, it was only a small sample of voters, and plenty of caveats were thrown in. “All the answers should be taken with a heavy pinch of salt,” wrote Kuenssberg in a piece published on Saturday. Even so, that’s one heck of a pinch of salt.

Of more importance, perhaps, was her conclusion. “In more than 20 years of covering politics, I have never sensed such a lack of belief in all our politicians' ability to solve the country's problems.” That, again, is a subjective view.

Given the limitations, was it worth doing this focus group exercise at all? Did we learn anything from hearing a Green voter call Rishi Sunak an “incompetent cretin”, or someone else criticise Keir Starmer as dull? Maybe a few smirks were raised, perhaps the odd press officer might take offence on behalf of their bosses, but such remarks would be seen by many as mild. All part of the cut and thrust.

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But what if someone went further than “incompetent cretin” and was not challenged on it? Should that be accepted as routine or is it something worth keeping an eye on?

Any broadcaster putting together a studio audience for a panel programme such as Question Time, or conducting focus groups, comes up against difficulties. I know because I was one of those soldiers.

For a start, the sample size has to be big enough to be representative but small enough to be manageable. Everyone has to be interviewed, often several times, and at length.

You need to know if a person is a party member. There is nothing wrong with that as long as members of other parties are represented to the same extent. You need a wide range of ages and a good geographical spread. You need to be able to justify your selections because there will be complaints afterwards, always from the parties and increasingly from viewers on social media.

There is no such thing as a perfect audience or focus group because humans are involved at every stage and humans can get things wrong. Even if audience selection could be done by artificial intelligence I dread to think how boring the result might be. There is no machine substitute for experience and gut instinct.

On the day itself the show has to entertaining. There is no point in having the ideal, perfectly balanced audience if no one is watching at home.

It is worth looking at focus groups if only because so many parties now use them as an add-on to polling. I would like to know how accurate they are, and how much is spent on them. To hear their backers, focus groups can yield information about voters and a constituency, but so too can a visit to the place and a read of the local paper. What television needs, together with the media in general, is to get out more.