Benedict Cumberbatch is praised for his nightly turn as Hamlet at London’s Barbican theatre, but it was his post-show stage performance that got audiences most excited this week.

After taking his final bow on Tuesday, the old Harrovian actor made an impromptu plea to the audience on behalf of Syrian refugees, in which he blasted the ‘utter disgrace of the British government’ for not doing enough to ease the crisis.

It came just four months after the Sherlock star was awarded a CBE – just one rung below a knighthood – in the Queen’s Birthday Honours list usually approved by Downing Street.

After his outburst last night one audience member tells me he then launched into the kind of foul-mouthed political rant that would have made even revolutionary Russell Brand blush.

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Impassioned: Benedict Cumberbatch made an impromptu plea to the audience on behalf of Syrian refugees after taking his final bow as Hamlet at London’s Barbican theatre

Imploring the audience to leave donations in buckets to alleviate the crisis, Cumberbatch shocked the theatregoers by shouting: ‘F*** the politicians.’

‘It was all very impassioned,’ I am told.

‘He began by reading out a poem called Home by [Somali poet] Warsan Shire. He then spoke about a friend who had come back from the Greek island of Lesbos a few months ago, where there were 5,000 people arriving a day, and how the [British] government was allowing just 20,000 refugees into the country over the next five years.

‘Then, out of nowhere came this “F*** the politicians” remark.

‘It’s not quite what you’d expect when you go for an evening with the Bard, but it got a few cheers.’

The Barbican is run by Sir Nicholas Kenyon, who would never have permitted such language in his days as controller of Radio 3.

Plea: Imploring the audience to leave donations in buckets to alleviate the crisis, Cumberbatch (pictured left and right with his wife Sophie Hunter) shocked the theatregoers by shouting: ‘F*** the politicians.’

There were also school children in the audience who had to listen to the actor’s unscripted salty soliloquy. Cumberbatch recently fronted a charity single, Help Is Coming, to raise money for the plight of refugees across the world, and used a screening of his latest film, Black Mass, to criticise Theresa May over the crisis.

‘Government is not doing enough,’ he said. ‘I’d like to sit down with Theresa May and get a full understanding of how her political economic model works . . . that there is virtually a zero degree of financial benefit from an immigrant population.’