Surveillance image of Suffragettes in the yard at Holloway prison

Surveillance photograph of two Suffragettes exercising in the yard at Holloway prison. This shot was taken by an undercover police photographer. The women are identified as 'Ball' and Mary Isaacs.
It is possible that the Suffragette on the left is Editha Warwick Ball who was sentenced to 6 months in Holloway in February 1913 for smashing 8 windows in London's West End.
Mary Isaacs, on the right of the image was arrested along with a number of other Suffragettes in March 1914 outside the offices of the Director of Public Prosecutions. Charged with obstruction she was sentenced to 14 days imprisonment.
Scotland Yard undertook covert photography of militant suffragettes from 1913. The images were used to identify suffragettes attempting to enter public buildings such as museums and art galleries, where they might attempt to damage the objects.