The stage version, which is being written by Antony Jay and Jonathan Lynn, writers of the original TV series, is due to embark on a regional tour in the summer with a view to a West End transfer at the end of the year.
Speaking to the Independent recently, Haig said: "We wanted to get it on before the election because it is about a government at the end of its days - but it was not to be. I suspect Gordon will be quite relieved because the scripts are all about a government which is on its way out, and everybody always thinks the Prime Minister is the current one.
"The TV series was first written during the time of Callaghan but was on air when Mrs Thatcher came to power. Everyone thought it was about her but in reality she wasn't the model for it at all!"