On 9 June 2017, Jon Snow began Channel 4 News by declaring: “I know nothing, we the media, pundits and experts, know nothing”. Like many commentators, he was acknowledging that broadcasters had misjudged Jeremy Corbyn’s electoral appeal and the popularity of Labour’s policies.

While pro-Corbyn alt-left sites have been the focus of attention post-election, broadcast news still remains the dominant source of information for most people. And nearly a third of people under 45 regularly tune into television news. In other words, broadcasters still matter in election campaigns.

Unlike the partisan world of newspapers and social media, however, broadcasters are duty bound to be impartial. In theory, this should mean broadcasters are free from the assumptions that shape the conventional wisdom of political journalism. But our research at Cardiff University suggests that, while Labour received ample airtime on television news, the prospect of the party – and its leader – being electorally successful was, at times, questioned by correspondents and in the use of vox pops.

We found that, broadly speaking, broadcasters gave roughly equal time to Conservatives and Labour. Theresa May’s appearances after the terrorist attacks in London and Manchester explain why the Tories, overall, received more airtime than Labour.

Political party airtime

Since Conservatives and Labour made up 82.4 per cent of all votes, broadcasters may feel satisfied they reflected the two horse race. But the smaller parties might understandably complain that overlooks the power broadcasters have in constructing, not just reflecting, public opinion.

BBC ITV Channel 4 Channel 5 Sky News Conservative 38.4% 36% 41.2% 39.8% 37% Labour 33.7% 33.9% 36.4% 29.2% 37.5% Lib Dems 8.5% 11.5% 9.8% 11.0% 11.1% UKIP 4.8% 6.6% 3% 6.2% 3.2% SNP 10.1% 6.1% 4.3% 7.8% 8.7% Greens 1.7% 2.6% 1.5% 1.6% 0.2% Plaid 1.1% 1.5% 1.5% 0.4% / Other 1.7% 1.8% 2.3% 4.0% 2.2%

Although the TV leaders’ debates gave the smaller party leaders prime time exposure, they were one-off events. It is the drip, drip, drip effect of appearing on television every night that is likely to lead to any meaningful impact on voters’ attitudes. Even the Liberal Democrats who received 10 per cent share of coverage – a fall of 7 per cent compared to the 2015 election campaign – found it hard to compete. As focus groups conducted by BritainThinks illustrated, many of their participants had not even heard of Liberal Democrat leader, Tim Farron.

Since the Democratic Unionist Party appeared just once or twice on each bulletin during the campaign, little wonder the party’s website crashed not long after the votes were counted. Outside Northern Ireland, most people in the UK had no clue about their policies when some form of coalition with the Conservatives was being reported.

Can you really trust a vox pop?

The impartiality rules enhanced Labour’s electoral fortunes, because it meant broadcasters engaged more substantively with their policy agenda rather than the internal divisions within the party. Research has previously shown broadcasters often focused on Corbyn’s leadership issues since his election in 2015, with hostile Labour MPs regularly appearing to criticise the direction of the party.

The 2017 election news agenda, however, was more policy driven than when Ed Milliband was leader, More than half of news items were about issues, compared to 38 per cent in 2015. The BBC News at Ten – the most watched evening bulletin with four million viewers – reported the highest proportion of policy items. It also supplied the most detailed analysis of issues over the campaign and had the lowest proportion of items without any policy information.

However, all broadcasters could have enhanced the independent scrutiny of policy issues. While politicians made up the vast majority of sources during the campaign, most bulletins left approximately 15 per cent of time for sources to question the parties’ proposals. It was less than half that amount – just 7.1 per cent - on Channel 5 news. The Institute for Fiscal Studies was regularly consulted, but there was little sustained use of other think tanks, academics in specialist areas (excluding psephologists promoting the horserace) or other information-rich experts.

With the exception of Channel 4, broadcasters spent far more time airing citizens’ views in either vox pops or extended interviews with voters. While some citizens gave valuable insights, with broadcasters targeting specific types of voters from marginal constituencies, they remain an editorial construction of public opinion. Most were fairly brief vox pops sampling a flavour of how people would vote, their views on party leaders and, to a lesser extent, their thoughts on the parties’ policy proposals.

Despite the popularity of Labour’s issues, vox pops often questioned Corbyn’s appeal to voters and his leadership qualities. On the BBC News at Ten, for example, after one positive comment about Corbyn’s integrity and authenticity, another member of the public had a longer exchange with the reporter about the Labour leader’s credentials:

Interviewee: Dead. He’s dead. He’s got no personality. No presence. He’s got no - he doesn’t look strong, he looks weak, he looks like a wet cod all the time. Reporter: Even though you are agreeing with all he says. Interviewee: I love the guy, I do, I’m honest, I would like him to win but he’s never going to win, never going to win, not in a million years.

In the run up to election day, Corbyn’s popularity was improving according to the polls – and now exceeds May’s – but this was not reflected in the editorial construction of public opinion. BBC presenter Jonny Dymond expressed regret about his use of vox pops after the campaign, acknowledging they had failed to accurately reflect the public’s changing mood towards Corbyn.

Similarly, in live two-way discussions, which made up almost a quarter of all election news items, Corbyn’s electability was, at times, questioned by correspondents. Rather than straightforwardly reporting the policy positions of parties, broadcasters often editorialised. As the former head of BBC television news, Roger Mosey, observed: “there have been times in this campaign when…we learn too much too quickly about a correspondent’s view of the agenda.”

After the local election results, for example, ITV’s political correspondent cast considerable doubt on how appealing Labour policies would be to most voters:

…if you look at the kind of policies that they’ve are putting forward, turning vast amounts of power to the trade unions, for example, talking openly about taxing the wealthy and the rich more without actually putting a figure on yet, as it were, on how rich you have to be to be taxed. These are policies that look ideologically pure but wouldn’t traditionally be seen as vote winners.

Given more than 40 per cent of the electorate ended up voting for Labour, the conventional wisdom about Corbyn’s brand of left wing politics has clearly been challenged.

Since much of the mainstream media has misjudged Labour’s electoral appeal, perhaps it’s time broadcasters focused more on scrutinising the parties’ proposals and less on what correspondents think about the political consequences of them. That way viewers can judge for themselves.

The Cardiff University study examined bulletins on Channel 5 at 5pm, Channel 4 at 7pm and at 10pm on BBC, ITV and Sky News.