It is strange how fringe theatre is cannibalising its own distant past at the moment, as if to validate an uncertain status and establish a canon for future reference, even aspiration, perhaps.

Howard Brenton’s 1984 trenchant, vivid study of Shelley and Byron arguing the toss about life, love and poetry with their radical concubines, Claire Clairemont and Mary Shelley (née Godwin), comes up a treat in Tom Littler’s sharp revival in the little Jermyn Street back parlour.

Originally, Brenton’s play – written for Foco Novo, an early Arts Council corpse, and revived at the Royal Court with Mark Rylance as Shelley– was a plangent postscript to failed relationships and a blueprint for new radicalism in the Thatcher years. There’s even a sardonic reference to the Arts Council’s “glory of the garden” report.

Now, the play jumps at you both in its attempt to define what poetry itself might do, and the self-mythologizing tendency of all four characters; Brenton writes them as if they are catching their own reflections, and it makes for a very stimulating exercise.

The first act captures that famous summer of 1816 on Lake Geneva, when the friendships are established and an evening of ghost stories suggests the idea of Mary’s Frankenstein.

The second act unfolds rapidly over Europe as Byron (David Sturzacker) seeks direct action, and Shelley (Joe Bannister) finds fame and a family while haunted by the ghost of his drowned wife (Emily Glenister) in London. Littler provides a deliquescent setting, designed by Will Reynolds, of teasing projections, a water trough and snatches of the Beethoven late quartets.

It might have been precious, but it all works really well, and the intensity of the poets - with some illuminating excerpts from texts on Plato, revolution and the triumph of love - is well matched by the performances of Joanna Christie as Claire and Rhiannon Sommers as Mary.

You get a real sense of what these people meant to each other, and how rare they were, not least when the envious critic and biographer Polidori, done with a fine, self-important sneer by Nick Trumble, claims his own place at the head of their table.