The title of the show derives from a phrase commonly used by BBC Announcers in the age of live radio, following an on-air flub: "I'm sorry, I'll read that again."
Garden's impressions of the rugby league commentator Eddie Waring and the Scottish TV presenter Fyfe Robertson, Oddie's frequent parodies of the game-show host Hughie Green, and Cleese's occasional but manic impressions of Patrick Moore (astronomer and broadcaster) also featured.
(In one episode of the serial "The Curse of the Flying Wombat", not only did Kendall play two characters in the same scene but so did Tim Brooke-Taylor, resulting in a four way conversation between the two actors).
Several cast members appeared in the radio comedy panel game I'm Sorry I Haven't a Clue, a spinoff from ISIRTA that has outlived it by decades.
In 2015, plans were announced for a live "Best Of" homage show, using material by Garden and Oddie reworked by Barnaby Eaton-Jones, Jem Roberts and Dirk Maggs and performed by Hannah Boydell, David Clarke, Barnaby Eaton-Jones, William KV Browne and Ben Perkins.
In February 2017, it was announced that the British tour would take place later in the year, with guest appearances by Garden, Oddie, Taylor and Jo Kendall.
[7] In 2019 four new episodes with the slightly modified title "I'm Sorry I'll Read That Again... Again" were recorded and broadcast on Radio 4 Extra with some original cast including Tim Brooke Taylor, together with newer performers such as Barnaby Eaton-Jones.
A vinyl compilation album of sketches was released on the Parlophone label in 1967, and later reissued on a double cassette by EMI in 1993 alongside the London recording of Cambridge Circus.
Another compilation was released by BBC Records in 1978, reissued on CD in 2011 as part of the Vintage Beeb range.