Song to the Men of England
I.
Men of England, wherefore plough
For the lords who lay ye low?
Wherefore weave with toil and care
The rich robes your tyrants wear?II.
Wherefore feed and clothe and save
From the cradle to the grave
Those ungrateful drones who would
Drain your sweat—nay, drink your blood?III.
Wherefore, Bees of England, forge
Many a weapon, chain, and scourge,
That these stingless drones may spoil
The forced produce of your toil?VI.
Have ye leisure, comfort, calm,
Shelter, food, love’s gentle balm?
Or what is it ye buy so dear
With your pain and with your fear?V.
The seed ye sow, another reaps;
The wealth ye find, another keeps;
The robes ye weave, another wears;
The arms ye forge, another bears.VI.
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.VII.
Shrink to your cellars, holes, and cells—
In hall ye deck another dwells.
Why shake the chains ye wrought? Ye see
The steel ye tempered glance on ye.VIII.
With plough and spade and hoe and loom
Trace your grave and build your tomb
And weave your winding-sheet—till fair
England be your Sepulchre.Reference: Poetry Foundation

Although I think he died before the Communist Manifesto, it sounds like Shelley could have been the poet laureate of communistic socialism. Pretty harsh at the end however which I take to mean the workers of England are ‘digging their own graves’ by submitting to the English social and economic systems.
I hear what you say Bill and Ozymandias is further evidence of his socialist position.