I always enjoyed the scene in Went The Day Well where little old lady Muriel George finishes off a stormtrooper with an axe; a film old enough to have Thora Hird and Patricia Hayes as little young ladies, though it has to be said neither was cast as the romantic interest.
However, yesterday I watched Pimpernel Smith which featured Mary Morris, whom I only remembered as a particularly wizened little old lady, as a glamorous Nazi spy, and very nobby she was too.