The fact that Jeremy Corbyn was elected Labour Leader despite the majority of the party’s MPs voting against him, was certainly a problem throughout his tenure. However, it seems we have a new twist to the saga: Mr Corbyn now appears to believe this was the principal reason why Labour failed to win the 2017 election – a victory that he was otherwise “absolutely confident” that Labour would have won “because it was all absolutely going our way”. What does the evidence suggest?

The open challenge to Mr Corbyn took place on 24 June, 2016, when the majority of his Shadow Cabinet resigned, provoking events that led to another Labour leadership election that he won comfortably in September. There were a variety of reasons why this June challenge to his leadership was mounted: one of them was that in May that year, Labour had lost 13 seats in the Scottish Parliament election after a nine point fall in its vote share (compared with an eight point increase in the Conservative vote that gained them an extra 16 seats). The Labour Party was led by Richard Leonard who was the favoured candidate of Mr Corbyn and his supporters in the earlier contest for the Scottish Party leadership. Also, in Wales, Labour lost outright control of the Assembly, with a near eight point fall in its vote. And in the local elections in England on the same day, Labour made a net loss of one council and eighteen seats. Also, in the EU referendum campaign that climaxed on 23 June, 2016, there had been fierce criticism of Mr Corbyn’s “lacklustre” support for the Remain campaign, despite the overwhelming majority of Labour MPs and party members backing that cause.

What did the opinion polls suggest throughout this period? The table above sets out the monthly average of voting intention polls starting immediately after the 2015 general election, through to the beginning of the 2017 election campaign period. What is clear is that Labour’s poll ratings remained dire throughout this period of Jeremy Corbyn’s leadership: there was no summit of public approval from which the party was toppled by treachery in the run-up to the 2017 election. When he was first elected, in September 2015, Labour’s monthly voting intention average was 32%: prior to the 2017 election, this share was only bettered once – in March 2016 – when it rose to 33%. The major rebellion against Mr Corbyn among his MPs occurred towards the end of June 2016, yet, in the first four polls of July, before Mrs May became Prime Minister, Labour’s poll ratings remained broadly the same (32%). It was only in the July polls following Mrs May’s election that Labour’s share dropped (to 29%). By April 2017, Labour’s average was 26% (compared with 32% in his first month as Leader; and 30% in the month he was re-elected.

The difficulty in sustaining Mr Corbyn’s assertion that he could have won in 2017 (for me at least) is the fact that in that election, when he was, apparently, undermined by his MPs, the party gained 36 seats (and lost six); and in the 2019 election, when he was in total control of the party and the election campaign and the PLP was quiescent, the party lost 60 seats (and gained one).

Because the polling suggests that, from the outset, the public had a negative view of Jeremy Corbyn that he could never shake off. He is the only Opposition Leader in Ipsos MORI’s monthly series of party leader favourability (begun in 1977) never to have received a positive rating. There never was a honeymoon with the British electorate subsequently wrecked by disloyal and poisonous individuals within the party: the longer voters knew Mr Corbyn, the more dissatisfied they seemed to become.

David Cowling

David Cowling is a political opinion polling specialist. Former editor of BBC Political Research and visiting senior research fellow at Kings College London. A full version of this article incuding several other tables is available here.