As the thirtieth anniversary of his death approaches, I’ve been thinking about the English composer Cornelius Cardew recently. Cardew’s musical career took an unusual turn in the 1970s along with his discovery of Marxism. After a stellar early career as an assistant to Stockhausen and a co-founder of the anarchic Scratch Orchestra, Cardew rejected and abandoned the avant-garde music scene and began to write populist political songs which drew inspiration from Mao's Yan'an talks on literature and art and resonated with the tradition of musical agit-prop from Brecht and Weill to John McGrath. By 1981, he had also become a relatively high-profile political organiser, going to jail on more than one occasion for his activities; this has led some to speculate that his death at the hands of a hit-and-run driver in December of that year was a political assassination effected by MI5.

Listening to Cardew’s political songs today, it is hard not to scoff at the crude objectivism, didacticism and Leninist langue de bois of lines like ‘In the 1840s Marx and Engels on our shores / organised and hammered out the objective laws’ and 'Persisting in the face of every difficulty / In 1979 was formed our new party / A glorious victory'. And yet, risible as such bombast is, you have to acknowledge the power of its unadorned sincerity. These songs now stand out not so much for their originality – a virtue which, by the late 1970s, Cardew had come to regard as trivial and bourgeois  – as for their urgency, energy and commitment, however glutinous their Maoist rhetoric.

Recently, arrests were made in Northern Ireland after two young men in Coleraine posted images of themselves on Facebook burning a red poppy. It is now, it seems, a criminal matter to oppose the symbols of the state - although the official charge is 'incitement to hatred'. The incident provides a high-profile example of how the British state is clamping down on expressions of political opposition in social media. This should in turn give pause for thought to those cyber-optimists and techno-determinists who still regard social media as inherently progressive, a site for democratic, uncensored self-expression. If only it were so. From its very beginnings, Facebook has been used by the police and secret services as a surveillance tool (an aspect of Facebook conveniently left out of the film The Social Network) and police are warning members of the public to 'be careful' about what they post on the site.

So what about the poppy? Like all symbols, the red poppy acquires its meaning from the social contexts in which it circulates. In Britain, the poppy is worn in the days around Remembrance Day and its most prominent wearers are the senior members of the ruling class, including the queen as well as top military and political figures - the very same people who organise and justify Britain's imperialist wars today. It is therefore necessarily a nationalist and militarist symbol. Usually this is made quite explicit by its defenders, who proclaim that they wear the poppy in remembrance of those who 'sacrificed' themselves for 'their nation' or to secure 'freedom' during the world wars of the twentieth century. Such defences would be a tough sell in Dresden or Hiroshima. Let's spell it out: the world wars involved massive and pointless loss of human life, as workers killed one another on behalf of their national ruling classes. Many of these men were conscripts and many of them were militant unemployed workers who had been blacklisted by employers and hence forced to join the army. After the First World War, the poppy was introduced to bind workers and their families to the nation state in order to ensure a ready supply a cannon fodder in the future. This cynical manipulation of the poppy's symbolism is nicely illustrated in Ken Loach's recent Route Irish, a film about a cover-up during the Iraq war, in which the only character to sport a red poppy is the oleaginous and corrupt ex-officer Haynes.

That the industrialised mass murder of the two world wars had nothing whatsoever to do 'protecting freedom' was quite apparent to many of those who actually fought in them. Britain's last surviving First World War veteran Harry Patch, for example, was very clear that the war was 'organised murder' that 'was not worth it'. Moreover, the allied victory over the fascists in the Second World War did not inaugurate an age of peace, as is often claimed by the pro-poppy lobby, but one of continuous slaughter, from Korea and Vietnam to Iraq and Afghanistan. Indeed, the global devastation wrought by the US and its allies since the Second World War has matched anything the Nazis could have brought about.

Of course, there are those who argue, whether fondly or cynically, that the poppy is a non-political symbol and that wearing it simply promotes awareness of all those who have died in wars. But this is at best disingenuous: people do not wear poppies to commemorate dead Vietnamese or Iraqis. Far from being a non-political symbol, the poppy - perhaps to an even greater extent than the Union Jack - is a potent emblem of state power. Its most vociferous proponents are the political and military elites which continue to send young people to their deaths in order to secure capitalist interests. At the time of writing, for example, the British Prime Minister and a royal prince are clamouring for the poppy to be worn by the England football team. Every news report referring to Remembrance Day refers to the 'sacrifice' of 'the fallen' (a phrase that excludes those brave men imprisoned, attacked or executed for refusing to participate in the wars) and draws parallels between the allegedly 'just wars' of the twentieth century and Britain's current violence overseas ('And now, over to Camp Bastion...'). It was not always thus; when I was a child in the 1970s, the red poppy was not such a big deal. But today it is at the heart of an orgy of nationalist and imperialist sentiment.

The Coleraine case is not the first instance of poppy-burning that has been dealt with by the police. In 2010, members of the group Muslims Against Crusades, which the Daily Star called 'poppy-burning scum', were fined for burning poppies during a protest. Such repression is to be expected: as the working class struggles to find its voice internationally, the ruling class will increasingly seek to rally us around its patriotic paraphernalia in the name of freedom. But the poppy, like the flag, is a symbol of slavery, not liberation. We will only be free when we reject our be-poppied masters and begin to organise society according to our own interests - a society without wage slavery or war. In the meantime, we should express solidarity with all those who are being prosecuted for defacing the cherished symbols of the nation state.