Shelleyism
Percy Bysshe Shelley instead of dying prematurely of drowning in 1822 at the young age of 29 lives til 1862 til the ripe age of 70.
Importantly, and most immediately post divergence in this TL he finishes and publishes his what can only be described as a manifesto in 1825: A Philosophical View of Reform
In OTL this work would be published posthumously in 1920. However even in its draft form can be seen a very developed socialist view of the labour theory of value and economic class, e.g. "For fourteen hours’ labour, which they do perforce, they receive—no matter in what nominal amount—the price of seven. They eat less bread, wear worse clothes, are more ignorant, immoral, miserable and desperate. This then is the condition of the lowest and largest class, from whose labour the whole materials of life are wrought, of which the others are only the receivers or the consumers.
Also despite his philosophical and poetic prowess he maintains a remarkably realistic outlook on progress, advocating gradual reform, yet he also does not rule out insurrection: "The last resort of resistance is undoubtedly insurrection. The right of insurrection is derived from the employment of armed force to counteract the will of the nation."
His views of organising are also lucid: "The true patriot will endeavour to enlighten and to unite the nation and animate it with enthusiasm and confidence. For this purpose he will be indefatigable in promulgating political truth. He will endeavour to rally round one standard the divided friends of liberty, and make them forget the subordinate objects with regard to which they differ by appealing to that respecting which they are all agreed. He will promote such open confederation among men of principle and spirit as may tend to make their intentions and their efforts converge to a common centre. He will discourage all secret associations, which have a tendency, by making the nation’s will develop itself in a partial and premature manner, to cause tumult and confusion."
Shelley here shows a a remarkable similarity of course to Marx etc here in his views. Where he can influence far greater however is the spread of socialist thought, republicanism and writings in English far earlier. The currency of his beliefs of course could gain strength in both the rise of Chartism, creating a far more radical wing, as well as supporting and influencing early trade unionism such as the Tolpuddle Martyrs.
Whilst most famous for his poetry, his politics is to be seen in his poetry, most famously in The Masque of Anarchy but also in many other poems, such as A Song to the Men of England:
"The seed ye sow, another reaps;
The wealth ye find, another keeps;
The robes ye weave, another wears;
The arms ye forge, another bears.
Sow seed—but let no tyrant reap:
Find wealth—let no imposter heap:
Weave robes—let not the idle wear:
Forge arms—in your defence to bear."
Yet Shelley was also both the budding philosophical and scientific prodigy. In A Refutation of Deism Shelley in 1814 wrote: "The laws of motion and the properties of matter suffice to account for every phenomenon, or combination of phenomena exhibited in the Universe. That certain animals exist in certain climates, results from the consentaneity of their frames to the circumstances of their situation: let these circumstances be altered to a sufficient degree, and the elements of their composition, must exist in some new combination no less resulting than the former from those inevitable laws by which the Universe is governed."
Here Shelley, as he does elsewhere, nigh encompasses the later dialectical materialism of Marx and Engels in OTL. As such, Shelleyism can bring about an ideology roughly the same as today's Marxism with the twist of a few things. Firstly, it is born of an English speaker, meaning the production, distributing and absorption of radical socialism can commence earlier.
Secondly, Shelley being a poet imbues what a stodgy dry translations of Engels, and particularly Marx as the founding articles of scientific socialism with a far more poetic flourish. In his Notes to Queen Mab in 1816 Shelley wrote (the poem was illegally printed and widely distributed amongst Chartists IOTL): "There is no real wealth but the labour of man. Were the mountains of gold and the valleys of silver, the world would not be one grain of corn the richer; no one comfort would be added to the human race. In consequence of our consideration for the precious metals, one man is enabled to heap to himself luxuries at the expense of the necessaries of his neighbour; a system admirably fitted to produce all the varieties of disease and crime, which never fail to characterize the two extremes of opulence and penury."
I conclude that Shelley can imbue the wrath of OTL Marxism with the poetry and heart of the romantics whilst creating a scandal only Lord Byron could dream of.