The contrast between the scale of his real crime — helping to start a war that left a million people dead, created the Isis terror group and destabilised the whole of the Middle East — and the misdemeanour for which he has finally been called out brings to mind murderous mafia boss Al Capone finally going to jail for tax evasion.

Even so the celebration we see from so many socialists at the news is justified. Ever since 2015 the Labour Party machinery has seemed to let rightwingers off the hook for breaches of discipline while hounding supporters of the party’s twice-elected leader Jeremy Corbyn.

During the 2016 leadership election thousands of members were suspended or expelled on the flimsiest of pretexts, including for having retweeted expressions of support for the Greens or Scottish Nationalists in the past (making a mockery of the idea that the party sought to attract people who had previously supported other parties) in a transparent though futile bid by then general secretary Iain McNicol to prevent Corbyn from winning.

The party machine also sat on complaints of anti-semitism, allowing these to go uninvestigated so that Corbyn could later be accused of failing to act. Recent reports suggest this sabotage extended to staff hostile to Corbyn shredding documents when they left but keeping copies that could be passed to the media, to actively prevent Labour from dealing with a problem that could then be laid at its door.

The replacement of McNicol by Jennie Formby has led to a huge improvement in the way the party treats its members and investigates complaints against them. Complaints raised by Corbyn in 2016, that the party was expelling members without even telling them why, can no longer be levelled at it.

Even so major injustices persist. Marc Wadsworth, the anti-racism campaigner booted out merely for saying MP Ruth Smeeth was working “hand in hand” with the Daily Telegraph, remains expelled.

Many Labour members will have felt double standards applied when Derby North MP Chris Williamson was suspended, again for comments many on the left would have agreed with. These stated that the party was “too apologetic” not about anti-semitism but about its record of fighting it, which Williamson rightly argued was better than that of other parties in Parliament.

Williamson’s suspension followed a pile-on by right-wing MPs demanding it in a letter to the leader. Yet when constituency Labour parties sought to express their opinions they were told not to make political interventions on a disciplinary matter (or, in a Freudian slip by Stephen Kinnock, told that “political interference in political disputes is not allowed.)”

The constant backbiting and sabotage by some MPs and Labour grandees has been allowed to go too far and the sense that they should face consequences for undermining the party is widespread among Corbyn supporters. Campbell’s expulsion hopefully shows that Labour is getting a grip.

But while disciplinary action may be appropriate in some high-profile cases, the very real problem of MPs who would rather lose an election than see Corbyn in Number 10 — and could act to prevent implementation of the party’s radical programme if he does make it there — ultimately demands a political solution rather than an administrative one.

Labour should embrace the principle that each parliamentary candidate should be selected democratically by their local party ahead of each general election, whether or not they are the sitting MP, to move beyond the sense of entitlement to “jobs for life” that disfigures Westminster.

And the leadership should give less ground to politically motivated attacks on its own supporters and prevent them becoming sacrifices to appease enemies who will not be satisfied unless the socialist revival in Labour is comprehensively crushed.(IPA Service)