Not surprisingly – given this newspaper’s history – the Labour leadership race, and in particular the candidacy of Jeremy Corbyn, has generated powerful feelings among readers, not all in favour of the Guardian’s coverage. “Had enough of your paper,” said the subject line of an email from one reader, who went on to say: “I’ve been a regular reader of the Guardian (Manchester Guardian as was) since 1958. Despite the low point reached in the 60s when you supported the US war in Vietnam for a while, I still continued with it. But your sustained, arrogant, specious and just false reporting of Corbyn’s candidacy is too much. I am not a member or even supporter of the Labour party but your scurrilous coverage has convinced me that your paper no longer lives up to the label. I shall no longer … buy it nor view it online. Goodbye.”

Lost cause or no, I felt it only courteous to reply: “I’m sorry that you are leaving and I will be looking at the Guardian’s coverage of Jeremy Corbyn to test your theory, but I just wondered whether you’d read this [‘I don’t do personal’, 17 June], or this [No wonder Jeremy Corbyn’s opponents are so rattled, 8 July], or this [Jeremy Corbyn has the one Blairesque trait the Blairites don’t get, 20 July].” These were articles that could be described as showing a measure of support for Corbyn. There was also a piece by Seumas Milne with a sympathetic mention for the Labour leadership contender (There’s no reason to accept austerity. It can be defeated, 18 June).

The reader responded, putting me firmly in my place: “Yes, I’ve read the articles you refer to but they are outnumbered some five to one by the negative reports. Comment is perfectly legitimate, but the sneering, supercilious, specious and dismissive contributions masquerading as ‘commentary’ belittle the claims of a ‘quality’ paper.”

Before attempting to assess the validity of the reader’s analysis – broadly shared by some other readers – I think his email reflects one or two other interesting aspects of the demographics of the Guardian’s readership and the left.

For a start, he is clearly an older person, someone who was reading the paper during the Vietnam war. Corbyn’s surge is attributed in some quarters to support among young people, but among Guardian readers that support is more likely to come from older members of the audience. Some research carried out by the Guardian’s consumer insight team, which regularly polls a sample reflecting our total readership, proves the point.

The research shows a clear pivot point, with those aged 45-plus significantly more likely to be left of centre than those aged below 45. However, readers aged 18-24 are more likely to be left of centre than those aged 25-44. So while most of the support for Corbyn would come from older readers, there is some evidence of a resurgence among the really young.

Research carried out by the Guardian’s consumer insight team showing the personal political stance of readers by age

Last Thursday, the team polled a different group, this time 630 members of the Guardian’s core readership in the UK, to find out who readers are supporting in the Labour leadership election and what they think of coverage so far. Among the key findings were:

• Among those expressing an opinion, 76% of readers believe that our coverage of the contest so far has been “fair and balanced”. However, 24% of readers disagree, and among Corbyn supporters this figure increases to 36%.

• 51% of those core Guardian readers polled say Corbyn is their preferred choice as the next Labour leader. He leads his rivals by some way, with just 7% supporting Yvette Cooper and 6% supporting both Andy Burnham and Liz Kendall.

• A significant minority of core readers are able to vote in the leadership election: 15% of those the team spoke to are members of the Labour party and a further 9% are registered supporters eligible to vote in the election.

• 53% of core readers say that the Guardian should not endorse any of the four candidates.

Turning back to the concerns of those who have complained to the readers’ editor’s office and commenters below the line, I read or viewed 43 pieces of journalism published between 21 and 30 July. This is not a scientific piece of research – we don’t have the resources – but an attempt, led by some of the readers’ comments, to gain a snapshot of the coverage.

While acknowledging that mine would be a subjective view, I tried to apply some basic rules to judging whether something was skewed in the case of a news story or when judging comment pieces.

In terms of the spread, there were 37 articles – the other six pieces of journalism were videos or cartoons – about Corbyn over the period against 23 for all the other election candidates put together. Of the total of 43 pieces, 16 broadly reflected opposition to the Corbyn candidacy, either through reporting of others’ comments or in straightforward opinion pieces, of which there were seven.

An example that reflects the concerns of readers came in an early online version of a news story headlined “Jeremy Corbyn warns ‘naughty people’ to leave Labour party alone”, published at 12.10pm on 28 July.

The first paragraph says: “Jeremy Corbyn has told ‘naughty people’ on the left and right of politics seeking to infiltrate the Labour party in order to vote in the leadership contest to leave the party alone.”

“Naughty people” is an odd turn of phrase for Corbyn to use, and indeed it wasn’t his but that of his interviewer on Radio 4’s Woman’s Hour when asking him a question about the potential for entryism skewing the leadership election. Corbyn merely used her phrase when replying.

I agree with readers who felt that not making clear he used the phrase in answer to a question held him up to ridicule. The online story was updated and by the time that story appeared in the print edition for the Guardian the following day the context was made clear. It falls into the “beardy weirdy” narrative that seemed to flavour some of the early coverage, not just in the Guardian but also right across Fleet Street. Readers find it patronising, even those who don’t belong to the Labour party.

Seventeen of the 43 pieces struck me as neutral, such as straightforward news stories or newspaper roundups of coverage. However, I have also included in that the editorial of 24 July, which I think sought to project fairly all the candidates as looking too much to the past, whether on the left or the right. During the period between 21 and 30 July, there were 10 pieces that could broadly be described as either being comment pieces in favour of Corbyn or news stories reporting positively about him.

As the narrative grew that Corbyn is enjoying a surge among younger people, the Guardian also ran a feature headlined “Corbyn has given young people like me new hope in politics. Labour must listen” on 24 July. But in the early days of Corbyn’s charge, the readers rightly got a sniff that on occasions we weren’t taking him seriously enough. That has changed, and there is still much coverage to go before the ballot closes on 10 September.

I can’t find any evidence that the negative pieces outnumber the positive pieces by as much as “five to one”, although that view is strongly held by some. Anyway, tallies of positive and negative pieces are a dangerous measure, as the Guardian should not be a fanzine for any side.

• This article was amended on 3 August 2015. An earlier version failed to make clear that Elliott reviewed a total of 43 pieces of journalism, of which 37 were articles and six were either videos or cartoons. All 43 were either read or viewed.

