Poem of the week: England in 1819 This week, a furious sonnet from Shelley whose attack on the ruling classes retains its power two centuries on

A Madame Tussaud's waxwork head of King George III Old, mad, blind, despis'd, and dying ... That most courtly of forms, the sonnet, turns against the court, among other power structures, in this week's choice. Shelley's extraordinarily-shaped "England in 1819" is centaur-like, its majestic, nearly Petrarchan opening sestet fused with a heavier, rougher octet. The octet's rhymes partly interlock, but the Petrarchan scheme dissolves with the two sets of rhyming couplets – the centaur's hooves. You can almost hear the angry howl of an invisible people rising up against their useless royal family and treacherous government. Grammatically, it's all of a piece. The swelling roll-call of injustice consists of main clauses unresolved until the 13th line. It's almost a list-poem, a piling-on of sound-bites which, for a modern writer, might not demand the syntactic resolution Shelley eventually provides, and which therefore surprises us so effectively. In microcosm, the same process occurs in the build-up of splendidly simple and exact adjectives in line one. The hapless George III (who was to die the following year) stands before us with a Lear-like pathos. He is despised and mad and blind (uncomprehending): he is old and dying. Shelley enjoys paradox throughout this sonnet and here the tone is more horrified than hating. But there is no sympathy for the heir to the throne, the dissolute Prince Regent ("a corpulent Adonis of 50", as Shelley's friend, Leigh Hunt, rather mercifully described him). In the vividly alliterative line, "A people starv'd and stabb'd in the untill'd field", we seem to hear the swords cutting through skin and tendons as troops ride in to instigate the infamous Peterloo Massacre. The trope by which this army becomes a "two-edg'd sword" consisting of "liberticide and prey" is more obscure. Paradox is the clue: the killer of liberty and his prey, liberty itself, are both destroyed. "All they that take the sword shall perish with the sword"(Matthew, 52). Christ said it more concisely, but Shelley's oddly sorted nouns forge their own hobnailed eloquence. The princes are dregs, the royal line a muddy spring, the rulers, engorged leeches: these plain, ugly metaphors are as exact as they are obvious. But then comes further obscurity. In line 12, is the Senate (parliament) equated with "Time's worst statute unrepeal'd" or is the "worst statute" another addition to the list of evils? Some commentators say that Shelley means the 1801 Act of Union between England and Ireland. But the metaphor of parliament itself as a rotten law, convoluted though it is, remains intriguing, and the dash suggests this should be the primary reading. When the poem finally reaches its apogee, its main verb, what do we learn? A further metaphor is heaped on top of the rest like a truckload of earth – all the horrors are mere graves, redundant in the dreamed-of new dawn. The sonnet abruptly "turns" with the hastily-sketched millenarian image of Liberty triumphant. "England in 1819" is a young man's poem (as, of course, are all Shelley's poems, including the magnificent "Mask of Anarchy", written in the same year), and it has its awkward moments. But youth's idealism is also its virtue. There is no shallow self-display in Shelley's anger. Sincerity, that unfashionable emotion, gives the poem not only its splendid energy, but an authority beyond the writer's years. The sonnet is powered by the momentum established in the sestet, and somehow maintains the intensity of its indignation through the weaker octet – because the political emotion is genuine. How pertinent those lines about the rulers "who neither feel, nor see, nor know" are to England, 2009, with its bankers unqualified to bank and its cabinet ministers unqualified, it so often seems, to (ad)minister. Where are today's Shelleys? Why can't political poetry be as good as any other? Distrust anyone who says the postmodern muse should be above such things. England in 1819 An old, mad, blind, despis'd, and dying king, Princes, the dregs of their dull race, who flow Through public scorn – mud from a muddy spring, Rulers who neither see, nor feel, nor know, But leech-like to their fainting country cling, Till they drop, blind in blood, without a blow, A people starv'd and stabb'd in the untill'd field, An army, which liberticide and prey Makes as a two-edg'd sword to all who wield, Golden and sanguine laws which tempt and slay, Religion Christless, Godless – a book seal'd, A Senate – Time's worst statute unrepeal'd, Are graves, from which a glorious Phantom may Burst, to illumine our tempestuous day.