Margaret Elise Harkness (28 February 1854 – 10 December 1923), also known under her pen name John Law, was an English radical journalist and writer.

[4] After attending a finishing school, Stirling House in Bournemouth, she left home at the age of 23 to make her living.

Harkness lived in various locations in London, occasionally with her cousin, Beatrice Potter (who later married Sidney Webb).

Beatrice Potter had a difficult relationship with a Radical politician, Joseph Chamberlain, that ultimately foundered.

[1] She was introduced to socialism and a group of people who based themselves at the British Museum Reading Room; her friends included her sister Katie, Eleanor Marx, Olive Schreiner, and Annie Besant.

[8] In 1905 she published George Eastmont: Wanderer about her life during the 1889 Docks strike when she was briefly a member of the Social Democratic Federation.

Her book In Darkest London documents poverty in the East End and the Salvation Army's approach to the problem.