THE murder of Sharon Tate and others – the subject of Quentin Tarantino’s current offering Once Upon A Time In Hollywood – is often seen as a marker of the end of the 1960s; a grotesque symbol of how idealism can degrade into decline and horror. The truth isn’t so neat. Charles Manson wasn’t a hippie but a deranged white supremacist, and a week after the murders, half-a-million long-hairs and drop-outs enjoyed Woodstock, supposedly without violent incident.

As with Tarantino’s flick, David Edgar knows very well the difference between complex reality and the relative simplicity of artifice: he’s spent much of his life writing political dramas, some of which have been staged at the National Theatre and the by Royal Shakespeare Company.

Part autobiographical one-man show, part provocation, Trying It On sees him make his first stage performance since his student days: a time of campus radicalism and the racist right marching in the streets.

Now something of an establishment figure himself, the playwright is confronted by his younger self – “a patronising, pompous prick” – who asks 71-year-old Edgar if they share the same beliefs.

It’s a risky, revealing premise that this consummate old hand riffs off well, using interview footage with other notables from the time reflecting on how the student movement splintered and mutated over the years and how some former revolutionaries voted for Thatcher a decade later.

It prepares the ground for insights into Brexit and the rise of the populist right in a twist which lets few of us off the hook.

Until tomorrow, Traverse Theatre, Edinburgh, today 7pm, tomorrow 10pm, £15 to £22. Tel: 0131 228 1404. www.traverse.co.uk