London: The Oscar-winning actress was discussing her role in the re-make of Arthur and John Gielgud`s part in the original when presenter Sian Williams remarked that he was famous for swearing a lot.
Dressed in a demure yellow cardigan and sophisticated matching skirt, Mirren clearly suffered a case of speaking before thinking.
‘Well, in that sort of wonderful voice he had... You little s***,” a newspaper quoted the veteran actress as saying.
Mirren immediately realised her mistake and covered her mouth before saying: ‘I``m so sorry.’
She then issued a cheeky grin to the camera with her hand placed under her chin.
This is not the first time Mirren has been caught out with a spot of potty mouth.
In 2007, she swore on camera during a red carpet interview at the BAFTA.