As mentioned in the tributes paid to Keith, he was a long-time activist within the peace movement, researching the Gandhian movement, working within CND, and a driving force in the co-founding of The Institute of Law and Peace, INLAP, which led on to the establishment of the British branch of the World Court Project. Perhaps his greatest achievement was his contribution to the success in 1996 with the Advisory Opinion of the International Court of Justice essentially outlawing nuclear weapons.
His only published book: https://www.amazon.com/Hiroshima-Hague-Guide-World-Project/dp/9291230022
Now available to read here: http://www.disarmsecure.org/Hiroshima%20to%20Hague.pdf
Other writings at: http://www.worldcat.org/search?q=au%3AMothersson%2C+Keith%2C&qt=hot_author
A selection below of his various other related activities…
The Institute for Law and Peace – http://www.inlap.freeuk.com/publications.htm
The International Peace Bureau – http://ipb.org/web/