LABOUR peers splashing cash on a Guardian advert attacking Jeremy Corbyn only serves to underline how important it is for the left to take the fight to the enemy.

It should hardly need saying, since it has been pointed out repeatedly, that the lords’ assertion that Corbyn has “allowed anti-semitism to grow in our party” is a lie.

Polls show both that Labour members are less likely to be anti-semitic than the public at large and that anti-semitic prejudice among them has declined since Corbyn became leader.

It is also well attested that the party’s process for handling accusations of anti-semitism has improved significantly since the socialist Jennie Formby replaced the anti-Corbyn Iain McNicol as general secretary.

Unfortunately it does need repeating, since Britain’s monopoly media giants from the Guardian to the BBC have sullied themselves in pushing a false narrative around anti-semitism in Labour motivated by a determination to unseat Corbyn and defeat its socialist spring.

For immigrant-bashers like former home secretary John Reid, who left the cabinet to take up a post at disgraced private security firm G4S, to declare that Corbyn has “failed to defend our party’s anti-racist values” shows staggering cynicism.

Corbyn has spoken of learning the importance of the fight against anti-semitism from his mother, who took part in the 1936 Battle of Cable Street when Communists and the East End Jewish community saw off Oswald Mosley’s Blackshirts.

Corbyn co-ordinated local councillors and anti-fascists to stop a National Front march from Ducketts Common in north London in 1977. He was also arrested for protesting against apartheid.

It would be tempting to say Reid is getting payback for Corbyn’s support for the family of Angolan deportee Jimmy Mubenga, who died under restraint by G4S guards while Reid was raking in almost £50,000 a year from the firm and whose widow Makanda Kambena was joined by Corbyn in her campaign to get an inquiry into his death.

That episode might be instructive as to the characters of the two politicians but it implies a desire for personal vengeance when Reid, like the other lords, is fighting a battle on behalf of the British Establishment.

In this fight anti-semitism is only the weapon of choice because Corbyn’s enemies have worked out it cuts deep, when alternative lines of attack ranging from the feeble to the preposterous (that he doesn’t respect the monarchy, that he’s scruffy, that he spied for communist Czechoslovakia, that he sympathises with terrorists and other such nonsense) have failed to resonate.

Although Corbyn’s long support for the Palestinian cause prompts hostility from the Israeli government’s supporters in this country, even that is secondary, except insofar as it points to his anti-imperialist outlook more generally.

This is not ultimately about defending Israel but about bringing Corbyn down and removing the threat of a fundamental shift in power and wealth to ordinary people, away from the banks, the property speculators and the transnational corporations.

That is why the left needs to unite around Corbyn and emphatically refute these dishonest slurs.

It also means being wise to faux concern from Blair-era party chair Clive Soley, who laments that the party is “haemorrhaging support” and could “die” over the course of two general elections as the Liberals did a century ago.

Soley may not have noticed that Labour won its biggest vote share increase since 1945 with Corbyn at the helm but he probably is aware that its current polling difficulties are both exaggerated by the media and influenced by the constant stream of Labour politicians taking to the airwaves to denounce their own party.

Labour has proved it can turn poor polling around in a mass campaign. But in government it will struggle to deliver anything radical unless those forces in the party irredeemably hostile to Corbyn are beaten for good.