Star Wars actor Oscar Isaac made a surprise appearance at Letters Live to read out a letter by Obi Wan Kenobi actor Sir Alec Guinness - in which he branded co-star Harrison Ford a "languid young man".
Writing during filming of the 1977 film Star Wars: A New Hope, Sir Alec complained: "Can't say I'm enjoying the film."
American actor Isaac, who plays Poe Dameron in Star Wars: The Force Awakens, joked to the audience at Freemasons' Hall in London that he would not even attempt an impression of Sir Alec as he read out his correspondence.
The late actor wrote to his friend Anne Kauffman: "New rubbish dialogue reaches me every other day on wadges of pink paper, and none of it makes my character clear or even bearable."
He added he was off to the studio to work with "Mark Hamill and Tennyson (that can't be right) Ford. Ellison? No! Well a rangy, languid man who is probably intelligent and amusing."
Inspired by the best-selling Letters of Note series and website, as well as Simon Garfield's book To The Letter, Letters Live sees actors and performers reading out literary correspondence to a live audience.
Benedict Cumberbatch, who took part in the event alongside his wife Sophie Hunter, channelled former Sherlock Holmes actor William Gillette as he read out a letter by Mark Twain.
Gillette played the famous detective on stage in 1899 and made a Sherlock Holmes silent film in 1916.
While no voice recording of Twain has survived, there is a recording of his former neighbour Gillette doing his best impression of the author in 1934. However, 39-year-old Cumberbatch, who stars in the BBC's Sherlock, said he would not follow this guideline too closely.
The letter from Twain to the American poet Walt Whitman paid tribute to all the changes he had witnessed in the world over the course of his lifetime.
Cumberbatch and his Sherlock co-star Louise Brearley then performed letters between Bessie Moore and Chris Barker, two sweethearts separated by World War Two.
The Imitation Game actor Cumberbatch has been at the heart of Letters Live since the first event was held in 2013, embracing the challenge of performing others' correspondence.
Sunday evening's performance also saw a reading by theatre and opera director Hunter, 37, who has previously taken part in Letters Live events at Hay Festival alongside her actor husband.
She left the audience moved as she read out a letter from deaf and blind woman Helen Keller to the New York Symphony Orchestra, thanking them for the music which she had experienced through the radio by feeling the vibrations.