There are three one-hour plays in this lively Greek tragedy hotchpotch loosely based on Aeschylus’ Oresteia, presented by Phil Willmott’s Steam Industry Free Theatre on Thursday to Sundays in the concrete amphitheatre next to City Hall, Tower Bridge on one side, the Shard now on the other.

Well, there should be three. On press night we got through The Trojan Horse and Agamemnon alright with just an odd splatter of rain, but the heavens opened ten minutes into Orestes so that the new baby of democracy was, alas, stillborn.

Willmott himself, playing Aegisthus, Agamemnon’s murderer and lover of his wife, Clytemnestra, strode into the arena in his shiny silver suit and thanked us for coming and put us out of our misery. Actually, I wasn’t too miserable: the evening had gone fairly well thus far.

The first hour is a knockabout, Funny Thing-style send up of the abduction of Helen by Paris and the campaign to steal her back in the wooden horse that starts the war. Helen has chosen Menelaus from a “Troyzone” boy-band including Paris (“a poor man’s Peter André”), Agamemnon (bronzed and handsome Stephen Billingham) and Agamemnon’s friend, Odysseus, who has a wandering eye.

This section has lots of fairly good musical numbers by Alastair Craft and several degrees of audience participation: two chaps in the second row who volunteered some boats for the armada were dubbed “Achilles and Patroclus” by Odysseus, “renowned for their bravery in battle and their taste in interior design.” And Agamemnon lost an arm-wrestling contest with an “Amazonian queen” from the audience; she, for sure, was a girl.

In the second play, the tragic, anticipatory tone is restored by James Horne’s wheelchair-bound veteran, Natalie Campbell’s vitriolic, blood-curdling Clytemnestra and Ruth Pickett’s wildly prophetic Cassandra, transformed from her first play role of permanent wallflower “because she can’t keep her mouth shut.”

The great thing about the Scoop is a) that it’s free and b) you can pop in on any play at any time if you happen to be passing. “Agamemnon” palpably gripped some accidental tourists as the tension mounted and Clytemnestra strewed the palace approach with red petals. And the play ends with news of the soldiers turning against Agamemnon and the storm clouds gathering…which is exactly what happened.