The blonde actress in the 1969 film Battle of Britain is Susannah York.
She played the role of Elsa, a German woman who falls in love with a British pilot. York's role was a small but significant one, adding a layer of human drama to the film's depiction of the aerial battles between the Royal Air Force and the Luftwaffe.
While York was certainly a prominent actress, her role in Battle of Britain is not as well-known as some of her other performances, such as her Oscar-nominated role in They Shoot Horses, Don't They? (1969).
Despite the relatively small size of her role, York's performance in Battle of Britain was well-received by critics and audiences. Her portrayal of Elsa added a touch of romance and pathos to a film that was otherwise focused on the grim realities of aerial warfare.