Even Lewis Carroll and Edward Lear couldn't have penned literary nonsense quite like that of John Rees. "Socialists," he wrote in explanation for his opposition to the Iraq war, "should unconditionally stand with the oppressed against the oppressor, even if the people who run the oppressed country are undemocratic and persecute minorities, like Saddam Hussein."

Rees is a national officer of the Stop the War Coalition, the hotch-potch of Marxist-Leninist groups, trade unions, and the embers of the Campaign for Nuclear Disarmament, which was responsible for organising last month's protests against Operation Protective Edge.

But while its leadership hails from the outer reaches of the far-left galaxy, it nonetheless continues to exert a powerful gravitational pull on more mainstream thinking about Britain's role in the world. Last August, Stop the War was credited with playing a crucial role in ramping up the pressure which led to Ed Miliband's decision to "stop the rush to war" in Syria.

Many of those who have joined the Stoppers' marches over the years - including those against Israel's actions in Gaza - will have done so for the very best of motives. Sadly, however, as Rees's warped "anti-imperialist" world-view illustrates, there is something rotten at the heart of Britain's "anti-war movement", where, for some, the thirst for peace appears to produce a rather tolerant attitude towards bloodthirsty dictators.

Take Andrew Murray, the coalition's chair from 2001-11 and now a national officer. While acknowledging that a man responsible for the death of 20 million people used "harsh measures", Murray still found the need to ask, in a piece marking the 120th anniversary of Stalin's birth, why "hack propagandists abominate the name of Stalin beyond all others". Murray's day job is as chief of staff to Len McCluskey, the general secretary of Unite. And then there's Kamal Majid, alongside George Galloway, Tam Dalyell and Caroline Lucas, a vice-president of Stop the War. He was a founding member of the Stalin Society, which was established in 1991 to "defend Stalin and his work".

No war, yes, if there's no dictatorship or genocide

As Nick Cohen wryly suggested of Murray in 2003, "mass opposition to a war against a dictator who models himself on Stalin is being led by a man who is nostalgic for Stalin". Perhaps that helps explain why pleas by the democratic opposition to Saddam for "the imperative of freedom and liberation from fascism and dictatorship" fell on deaf ears. As Kurdish leader Barham Salih succinctly put it: "To those who say 'No war', I say, of course, 'yes', but we can only have 'No war' if there is 'No dictatorship' and 'No genocide'."

Unsurprisingly, beneath the guise of Stop the War's calls last year for respect for Syrian "rights of national sovereignty" lurked a rather less appetising outlook. In 2012, Majid described the Assad family as rulers "with a long history of resisting imperialism" who must be supported "because their defeat will pave the way for a pro-Western and pro-US regime". At a public meeting in May 2013 the coalition gave a platform to Issa Chaer, a lecturer at South Bank University, who told Press TV in 2012 that Bashar al-Assad was "now uniting the country". Six months later, it invited Mother Superior Agnes Mariam de la Croix, a nun who claimed the Syrian opposition staged the video of the Ghouta chemical weapons attacks which killed 1,500 people, to address its national conference. A storm of protest led her to her withdrawal.

In March, Lindsey German, Stop the War's convenor, blamed the encirclement of Vladimir Putin's Russia with "puppet regimes" for its aggression against the Ukraine, while also attempting to smear the Maidan protesters by warning darkly of the "fascist forces" in the movement. Anti-Americanism is thus the coalition's lodestar.

Stop the War has spent this summer simultaneously raging against Israel's "barbarism" and warning that it is "vital we oppose" American intervention to rescue the Yazidis from Isis.

Nonsensical as the Stoppers' views may seem, for the victims of Saddam Hussein, the Assads, Isis and Putin, the consequences of this anti-imperialism of fools is one Mad Hatter's tea party that's all too real to be fiction.