When I tweeted my post about the Guardian's ranking of the Ealing comedies, someone replied  that Passport to Pimlico is her favourite among them and that Margaret Rutherford's performance in it is wonderful.

That reminded me of a story from the memoirs of T.E.B. 'Tibby' Clarke, who wrote the screenplay for Passport to Pimlico.

He had written the part with Alastair Sim in mind, but when the time came to make the film, Sim was not available. The more that alternative actors were suggested, the more strongly the filmmakers felt that Sim was irreplaceable.

Then someone had a brainwave and suggested Margaret Rutherford. The mood brightened. 

"We'll have to rewrite the screenplay, of course," said one. When Clarke sat down with it, he found he had to change only one line.